TABLE 2.

Functions and mutant phenotypes of T4 gene products

Genea	Function of gene productb	Size (kDa)b	Mutant phenotype	Restrictive host or conditionc	Reference(s)
rIIA	Membrane-associated protein; affect host membrane ATPase	82.9	Rapid lysis; suppress T4 30 and some 32 mutations	Auxiliary; rex+ λ lysogens; P2-like HK239 lysogen; tabR	2-4, 56, 59, 95, 96, 106, 121, 159, 181, 184, 191, 198, 216, 224, 263, 292, 293, 365, 375, 441, 430, 431, 451, 504, 582, 768, 769, 774, 793, 810, 811, 834, 851, 874, 940, 1007, 1021, 1059, 1114b, 1159,
60	DNA topoisomerase subunit	18.6	DNA delay; rc = acriflavine resistance	Essential; 25°C or below	447, 450, 451, 452, 653, 654, 681, 801, 968, 1037
mobA	Pseudogene of Mob site-specific DNA endonuclease	4.2		Nonessential	E. Thomas, F. Zucker, and E. Kutter, unpublished data
39	DNA topoisomerase subunit; DNA-dependent ATPase; membrane-associated protein	58.0	DNA delay; rc = acriflavine resistance	Essential; 25°C or below; synthetic lethal with T4 49 and 17 mutations, or when host topoisomerase IV is poisoned with novobiocin	264, 297, 295, 296, 432, 447, 448, 449, 451, 452, 454, 571, 589, 653, 654, 708, 789, 768, 769, 801, 834, 853, 1006, 1037, 1047, 1059, 1216, 1236
goF = comC-α = go9H	Affects mRNA metabolism	16.7	Allows T4 growth in rho (nusD) hosts	Auxiliary	144, 431, 474, 879, 925, 956, 1028, 1044, 1045, 1062, 1154, 1241
cef = mb = M1 = motC	Processing of T4 tRNAs	8.5		Auxiliary; CT439; roc− hosts	431, 869, 870, 878, 937, 956
pseF = plaCTr5x?	5′ phosphatase			Auxiliary	956
motB		18.2	Affects middle transcription	Auxiliary	956
dexA	Exonuclease A	26.0		Auxiliary; restricted on optA hosts	308, 355, 431, 604, 737, 780, 956, 1152
dda = sud	DNA helicase; DNA-dependent ATPase	49.9	Suppress certain T4 32 mutations	Auxiliary; synthetic lethal with T4 59 mutations	45, 309, 369, 431, 481, 546, 547, 587, 588, 649, 680, 769, 780, 783, 956, 970; P. Gauss, personal communication
srd = dda.2	Postulated decoy of host σ70 or σS	29.1		Auxiliary	780
modA	Adenylribosylating enzyme	23.4	α subunits of host RNA polymerase are incompletely modified	Auxiliary	324, 431, 435, 780, 1011, 1077
modB	Adenylribosylating enzyme	24.2		Auxiliary	780, 1077
srh = modA.5	Postulated decoy of host σ32	8.1	Delays early T4 gene expression at high temperatures	Auxiliary	780
mrh	Affects phosphorylation of host σ32	18.5	Allows T4 growth in a σ32 host	Auxiliary	290, 780
soc	Small outer capsid protein	9.1	Unstable T4 capsids	Auxiliary	77, 89, 167, 431, 461, 462, 466, 675, 780, 916, 918
segF = 69	Intron-like endonuclease. A probable fusion protein, generated from 56 and 69 by hopping of ribosomes across a pseudoknot, is larger	26.2		Nonessential	51, 305, 677, 769, 780, 790, 783
56	dCTPase; dUTPase; dCDPase; dUDPase	20.4	Little DNA synthesis; unstable DNA	Essential	305, 347, 602, 605, 696, 769, 781, 783, 839, 1162
oriA	DNA replication origin; cis-acting sequences in 56, 69, and soc; primer transcript same as transcript for these genes		No DNA synthesis from oriA	Auxiliary	160, 674, 678, 691, 791, 1215
dam	DNA adenine methylase	30.4	No DNA adenine methylation	Auxiliary	112, 139, 395, 676, 677, 683, 742, 743, 921, 960, 961, 1072
61 = 58	Primase; requires interaction with gp41 helicase for priming at unique sequence	39.8	DNA delay	Auxiliary; 25°C or below; synthetic lethal with T4 49 or 17 mutations	17, 47, 60, 123, 154, 380, 415, 416, 421, 422, 652, 653, 667, 761, 768, 769, 783, 788, 801, 829, 826, 831, 970, 996, 997, 998, 1216
sp = 61.3 = rIV	Periplasmic protein	11.0	Rapid lysis; suppresses e lysozyme mutations	Auxiliary	2, 261, 492, 585, 851, 971, 1208
dmd = 61.5	Discriminator of mRNA degradation	7.0	Excessive mRNA degradation	Nonessential; suppressed by motA mutations	491, 493, 971, 1102/PICK>
41	Replicative and recombination DNA helicase; GTPase; ATPase; dGTPase; dATPase	53.6	DNA arrest; little DNA displacement synthesis	Essential	17, 54, 60, 154, 155, 184, 197, 227, 228, 264, 309, 424, 415, 416, 421, 451, 478, 479, 554, 593, 653, 652, 651, 761, 768, 769, 826, 831, 838, 930, 931, 950, 970, 1029, 1064, 1122, 1220
40	Membrane-associated protein initiator of head vertex	13.3	Polyheads	Auxiliary; high temperatures	89, 115, 116, 301, 416, 443, 500, 608, 693, 729
uvsX = fdsA	RecA-like recombination protein; DNA-ATPase	44.0	UV- and X-ray sensitive; recombination deficient; suppress 49 mutations	Auxiliary	26, 80, 82, 165, 182, 213, 254, 282, 283, 281, 301, 351, 384, 386, 392, 416, 423, 549, 572, 589, 686, 723, 739, 762, 768, 769, 938, 949, 950, 970, 1047, 1088, 1138, 1222-1225
segA	Site-specific intron-like DNA endonuclease	25.3		Nonessential	986, 988
β-gt	β-Glucosyltransferase	40.7	No β-glucosylation of HMC DNA	Auxiliary; Shigella	139, 316, 451, 615a, 757, 924, 1075, 1084, 1134
42	dCMP hydroxymethylase	28.5	Little or no DNA synthesis	Essential	60, 68, 124, 184, 264, 320, 348, 383, 451, 476, 475, 477, 598, 611, 612, 695, 698, 834, 1027, 1076, 1114a, 1165, 1192
imm	Inner membrane protein	9.3	No immunity to superinfection	Auxiliary	2, 3, 4, 166, 188, 665, 666, 836, 1113, 1232
43	DNA polymerase; 3′-to-5′ exonuclease	103.6	No DNA synthesis; mutator or antimutator activities of conditional lethals under semipermissive conditions	Essential; nonessential dsd mutants do not grow in optA hosts	1, 17, 20, 21, 23, 24, 36, 43, 53, 54, 57, 58, 60, 68, 94, 130, 212a, 229, 230, 231, 237, 264, 259, 289, 298, 334, 343, 394, 393, 451, 488, 495, 506, 507, 527, 529, 555, 581, 617, 645, 646, 653, 689, 768, 769, 826, 827, 828, 831, 834, 856, 857, 903, 904, 905, 906, 907, 908, 909, 910, 911, 912, 913, 914, 970, 978, 983, 1029, 1030, 1033, 1046, 1088, 1128, 1142, 1143, 1147, 1150, 1165, 1207
regA	Translational repressor of several early genes	14.6	Extended synthesis of several early proteins	Auxiliary; restricted in E. coli rpoB5081 at 42°C	9, 10, 19, 131, 320, 338, 484, 485, 503, 505, 637, 735-738, 835, 860, 951, 952, 953, 975, 1095, 1167, 1182
62	Clamp-loader subunit	21.4	No DNA synthesis	Essential	17, 20, 57, 60, 264, 310, 311, 312, 320, 451, 469, 470, 486, 487, 488, 616, 619, 653, 679, 826, 831, 834, 865, 864, 901, 902, 1089, 1217, 1227
44	Clamp-loader subunit	35.8	No DNA synthesis	Essential	20, 57, 310, 311, 312, 320, 469, 470, 486, 487, 488, 616, 618, 619, 679, 826, 831, 864, 865, 901, 902, 970, 1032, 1089, 1217, 1227
45	Processivity enhancing sliding clamp of DNA polymerase; and mobile enhancer of late promoters	24.9	No DNA synthesis; no late transcription	Essential	17, 20, 22, 264, 299, 310, 311, 312, 320, 334, 404, 405, 451, 469, 552, 552a, 616, 617, 619, 618, 653, 673, 679, 747, 786, 826, 831, 834, 865, 901, 902, 951, 952, 953, 970, 983, 1031, 1079, 1080, 1081, 1082, 1091, 1092, 1186, 1217, 1227
rpbA	RNAP-binding protein	14.7		Auxiliary	444, 552, 786, 1171, 1172, 1174
46	Recombination protein and nuclease subunit	63.6	Recombination deficient; DNA arrest; no host DNA degradation	Essential in B strains; mutants are “leaky” in some K strains	60, 68, 93, 111, 184, 195, 264, 345, 380, 403, 451, 605, 627, 668, 731, 740, 744, 768, 769, 775, 784, 1036, 1047, 1138, 1163, 1164
47	Recombination protein and nuclease subunit	39.2	Recombination deficient; DNA arrest; no host DNA degradation	Essential in B strains; mutants are “leaky” in some K strains	93, 345, 403, 605, 731, 744, 768, 769, 1036, 1164
α-gt	α-Glucosyltransferase	46.7	No α-glucosylation of HMC	Auxiliary	140, 316, 345, 437, 924, 1072, 1084, 1191
mobB	Putative site-specific intron-like DNA endonuclease	30.4		Nonessential	48, 1072
55	σ factor recognizing late T4 promoters	21.5	No late transcription	Essential	97, 98, 109, 310, 313, 311, 345, 404, 552, 635, 834, 895, 1038, 1082, 1171, 1173, 1174, 1186
nrdH = 55.7	Anaerobic nucleotide reductase subunit	11.7		Auxiliary	257, 368, 1085
nrdG = 55.9	Anaerobic nucleotide reductase subunit	18.2		Auxiliary	660, 1228
mobC = 55.10	Putative intron-like DNA endonuclease	24.0		Auxiliary	1072
nrdD = sunY	Anaerobic ribonucleotide reductase subunit; RNA contains a self-splicing intron	68.0		Anaerobic growth	39, 342, 882, 1053, 1086, 1203, 1229, 1237; M. Ohman-Heden, personal communication
I-TevII	Endonuclease for nrdD-intron homing	30.4		Nonessential	52, 178, 251, 342, 661, 662, 882, 993, 991, 1085
49	Recombination endonuclease VII	18.1	No resolution of recombination junctions; incomplete packaging of DNA; reduced heteroduplex repair, reduced DNA synthesis	Essential	39, 70, 79, 81, 82, 172, 213, 249, 250, 278, 300, 285, 330, 331, 332, 333, 350, 522, 523, 524, 525, 526, 541, 559, 669, 670, 740, 768, 769, 783, 788, 792, 793, 817, 883, 1025, 1030, 1029, 1047, 1083, 1085, 1226; G. Mosig and D. Powell, Abstr. Annu. Meet. ASM, p. 209, 1985
49′	Internal translation initiation product	11.9			39, 784, 788
pin	Inhibitor of host Lon protease	18.8	Degradation of amber peptides	Auxiliary	1005, 1012, 1085
nrdC	Thioredoxin, glutaredoxin	10.1		Auxiliary	64, 257, 341, 460, 632, 815, 816, 1066, 1085
mobD	Putative site-specific DNA endonucleasee	30.5		Nonessential	1072
rI = tk.-2	Membrane protein	11.1	No lysis inhibition	Auxiliary	3, 56, 224, 236, 851
tk	Thymidine kinase	21.6		Auxiliary	156, 157, 348, 604, 696, 733, 1112; Thomas et al., unpublished
vs	Modifier of valyl-tRNA synthetase	13.1		Auxiliary	688, 713, 842, 843, 1112
regB	Site-specific RNase	18.0	Misregulation of early genes; specific mRNAs stabilized	Auxiliary	156, 736, 942, 943, 955, 1106, 1112
denV	Endonuclease V; N-glycosidase	16.1	UV sensitive	Auxiliary	35, 219, 222, 223, 232, 304, 339, 575, 604, 620, 621, 622, 623, 656, 657, 685, 714, 715, 716, 718, 758, 806, 812, 813, 832, 862, 884, 885, 899, 969, 1110, 1111, 1112, 1117, 1120, 1151, 1212, 1213
ipII	Internal protein II	11.1∗ 9.9		Auxiliary	84, 88, 89, 442, 595, 604, 1093, 1112
ipIII	Internal protein III	21.7∗ 20.4		Auxiliary	84, 88, 89, 442, 434, 451, 595, 604, 802, 803, 804, 1093, 1112, 1114a
e	Soluble lysozyme; endolysin	18.7	No cell lysis	Essential, except when suppressed by sp and 5 mutations	2, 3, 4, 50, 261, 268, 346, 500, 594, 604, 704, 720, 787, 850, 871, 872, 948, 1050, 1099, 1158, 1193
nudE = e.1	Nudix hydrolase	17.0		Auxiliary	1204
goF3			Allow T4 growth in nusD rho hosts	Auxiliary	720, 1045
rnaC = species 1	Stable RNA			Nonessential	110, 302, 707, 870, 962
rnaD = species 2	Stable RNA			Nonessential	110, 302, 707, 870, 962
tRNAArg			psu4 opal suppressor	Auxiliary; CT439	5, 110, 284, 302, 328, 361, 366, 367, 501, 707, 710-712, 870, 962, 964, 1178, 1179, 1180
segB	Probable site-specific intron-like DNA endonuclease	26.2		Nonessential	110, 302, 604, 772, 988
tRNAIle				Auxiliary; CT439	302, 707, 962
tRNAThr				Auxiliary; CT439	302, 707, 962
tRNASer			psua; psub; psut; amber suppressors	Auxiliary; CT439	302, 707, 962
tRNAPro				Auxiliary; CT439	302, 707, 962
tRNAGly				Auxiliary; CT439	302, 707, 962
tRNALeu			psu3	Auxiliary; CT439	302, 707, 962
tRNAGln			psu2; SB	Auxiliary; CT439	302, 707, 962
ip1	Internal protein 1	10.2∗ 8.5		Auxiliary; CT596	6, 84, 87, 88, 89, 110, 442, 543, 595, 1093, 1112
57B		17.3		?	110, 280, 409, 410, 922
57A	Chaperone of long and short tail fiber assembly	8.7	Defective tail fiber assembly	Essential; bypassed by certain host mutations	110, 122, 186, 319, 391, 401, 409, 410, 699, 922
1	dNMP kinase	27.3	No DNA synthesis	Essential	110, 184, 241, 264, 348, 543, 696, 834
3	Head-proximal tip of tail tube	19.7	Unstable tails	Essential	7, 186, 264, 535, 536, 543, 648, 1124
2 = 64	Protein protecting DNA ends	31.6	Noninfectious particles with filled heads	Essential, except in recBCD hosts	28, 89, 186, 249, 250, 264, 543, 647, 1000, 1001, 1074, 1144
4 = 50 = 65	Head completion protein	17.6	Noninfectious particles with filled heads but tails attached at wrong angles	Essential	89, 249, 250, 264, 543, 787
53	Base plate wedge component	23.0	Defective tails	Essential	186, 249, 250, 530, 531, 532, 787, 1155, 1157
5	Base plate lysozyme; hub component	63.1∗ 44* 19	Defective tails	Essential	2, 186, 249, 264, 497, 500, 530, 531, 532, 787, 807, 1063, 1119, 1157
oriE	DNA replication origin; cis-acting sequences in genes 4, 53, 5; primer transcript in opposite orientation of gene 5 transcripts		No DNA synthesis from oriE	Auxiliary	378, 563, 641, 779, 1109, 1215; G. Lin and G. Mosig, unpublished data
repEB	Protein required for initiation from oriE	5.48	No DNA replication from oriE	Auxiliary; synthetic lethal with motA mutation	1109
repEA	Protein auxiliary for initiation from oriE	6.13	Anomalous DNA replication from oriE	Auxiliary	1109
segC	Site-specific intron-like DNA endonuclease	16.0		Nonessential	490, 641, 988, 989a; Lin and Mosig, unpublished
6	Base plate wedge component	74.4	Defective tails; permit plating of fiberless phage	Essential	186, 193, 249, 253, 264, 537, 1119, 1157; R. Marsh, personal communication
7	Base plate wedge component	119.2	Defective tails; permit plating of fiberless phage	Essential	186, 193, 249, 250, 253, 264, 537, 1119, 1156, 1157; Marsh, personal communication
8	Base plate wedge component	38.0	Defective tails	Essential	186, 250, 249, 253, 264, 537, 1119, 1156, 1157
9	Base plate wedge component, tail fiber socket, trigger for tail sheath contraction	31.0	No attachment of tail fibers	Essential	186, 250, 264, 535, 537, 562, 876, 1114a, 1155, 1157
10	Base plate wedge component, tail pin	66.2	Defective tails	Essential	186, 249, 250, 264, 272, 537, 726, 867, 868, 876, 1119, 1155, 1156, 1157, 1239
11	Base plate wedge component, tail pin, interface with short tail fibers, gp12	23.7	Defective tails	Essential	186, 249, 250, 264, 535, 537, 633, 868, 867, 876, 1119, 1155, 1157, 1239
12	Short tail fibers	56.2	Defective tails	Essential	122, 186, 391, 521, 535, 537, 745, 972, 1114a, 1155, 1157
wac	Whiskers, facilitate long tail fiber attachment	51.9	No whiskers	Auxiliary	186, 214, 745, 877, 1024, 1065, 1114a, 1188
13	Head completion	34.7	Inactive, but filled heads	Essential	89, 249, 250, 264, 973, 1114a
14	Head completion	29.6	Inactive, but filled heads	Essential	89, 250, 249, 264, 973, 1114a
15	Proximal tail sheath stabilizer, connector to gp3 and/or gp19	31.6	Defective tails	Essential	249, 250, 264, 272, 535, 537, 973, 1114a
16	Terminase subunit, binds dsDNA	18.4	Empty heads	Nearly essential	85, 86, 89, 90, 249, 250, 264, 286, 287, 642, 643, 644, 669, 802, 803, 873, 891, 1194
16′	Truncated C-terminal end
17	Terminase subunit with nuclease and ATPase activity; binds single-stranded DNA, gp16 and gp20	69.8	Empty heads	Essential	75, 85, 86, 89, 90, 249, 250, 264, 286, 287, 288, 433, 586, 631, 642, 643, 669, 746, 769, 784, 785, 873, 891, 892, 893, 1194, 1195, 1196
17′A	Terminase subunits with nuclease and	59.2		?	286, 287, 288, 333, 784
17′B	ATPase activity; internal transcription and translation in frame; does not bind ssDNA	57.1
17"	Terminase subunit with nuclease and ATPase activity (transcript processing and internal initiation of translation in frame); does not bind ssDNA; several additional proteins most likely initiated from internal ribosome binding sites of the 17 transcripts	46.8		?	286, 287, 288
18	Tail sheath monomer	71.3	Defective tails	Essential	29, 31, 186, 249, 250, 264, 272, 535, 537, 1096, 1119, 1157
19	Tail tube monomer	18.5	Defective tails	Essential	30, 186, 249, 250, 264, 272, 535, 536, 537, 1119, 1157, 1194
20	Portal vertex protein of the head	61.0	Polyheads	Essential	86, 89, 90, 238, 250, 264, 333, 608, 642, 643, 694, 990, 1114a
pip = 67	Prohead core protein; precursor to internal peptides	9.1∗ small peptides	Defective heads	Essential	89, 519, 1130, 1131
68	Prohead core protein	15.9	Isometric heads	Essential	89, 516, 518, 520
21	Prohead core protein and protease	23.3∗ small peptides	No or defective heads	Essential	89, 250, 264, 329, 414, 516, 517, 606, 608, 844, 845, 990, 1116
21′	Prohead core protein and protease (internal initiation of translation)	20.8∗ small peptides	Defective heads		414
22	Prohead core protein; precursor to internal peptides	29.9∗ small peptides	No or faulty heads	Essential	89, 250, 264, 270, 518, 595, 608, 728, 805, 844, 845, 990, 1094, 1093, 1114a
23	Precursor of major head subunit	56.0∗ 48.7∗ 43	No or faulty heads; gol mutations in gene 23 allow growth in lit hosts (CTR5x)	Essential; Gol peptide together with E. coli Lit, cleaves host EF- Tu	27, 65, 86, 89, 90, 158, 218, 225, 226, 250, 256, 260, 264, 270, 315, 396, 461, 466, 606, 608, 684, 719, 754, 825, 841, 854, 936, 1021, 1093, 1094, 1119, 1231
segD	Probable site-specific intron-like DNA endonuclease	25.6		Nonessential	490, 988
24 = os	Precursor of head vertex subunit	47.0∗ 46	No or faulty heads, osmotic shock resistance	Essential; bypassed by certain gene 23 mutations	8, 76, 89, 250, 262, 264, 396, 461, 606, 608, 634, 719, 1114a; G. Yasuda, G. A. Churchill, M. Parker, and D. Moorey, personal communication
rnlB = 24.1	Second RNA ligase	37.6		?	426
hoc = eph	Large outer capsid protein	40.4	Unstable capsids	Auxiliary	89, 167, 164, 168, 461, 462, 496, 916, 917, 1205
inh = lip	Minor capsid protein; inhibitor of gp21 protease	25.6		Auxiliary	496
segE	Probable site-specific intron-like DNA endonuclease	22.9		Nonessential	489, 490, 988
uvsW = dar	RNA-DNA- and DNA-helicase; DNA-dependent ATPase	67.5	UV sensitive; fail to unwind R-loops; suppress T4 59 uvsX, uvsY, and 46 mutations	Auxiliary	132, 195, 196, 207, 208, 212, 244, 722, 737, 768, 769, 1061, 1191, 1197, 1199, 1222, 1240
uvsY = fdsB	ssDNA binding, recombination and repair protein; helper of UvsX, inhibitor of endoVII	15.8	UV sensitive; recombination-deficient; repair-deficient, DNA arrest; suppress T4 49 mutations	Auxiliary	25, 44, 82, 182, 183, 195, 212, 213, 232, 357, 358, 380, 387, 392, 522, 542, 548, 589, 723, 724, 739, 768, 769, 1013, 1047, 1054, 1055, 1060, 1061, 1138, 1191, 1199, 1210, 1225, 1222, 1223, 1240
oriF = oriuvsY	DNA replication origin; cis-acting sequences in genes uvsY, uvsY.-1 and uvsY.-2; primer transcript same as uvsY, uvsY.-1 and uvsY.-2 transcript		No DNA synthes from oriF	Auxiliary	46, 133, 357, 378, 563, 574, 573, 576, 577, 678, 724, 779, 830, 1109, 1215
25	Base plate wedge subunit	15.1	Defective tails	Essential	186, 249, 250, 264, 356, 358, 357, 530, 531, 532, 540, 822, 819, 1057, 1155, 1157; B. Szewczyk and J. Nieradko, personal communication; E. Tourkin and B. Poglozov,
26	Base plate hub subunit	23.9	Defective tails	Essential	186, 250, 264, 357, 531, 540, 567, 820, 958, 1108, 1157, 1240
26′	Internal in-frame translation initiation	12		?	357, 823
26"	Internal out-of-frame translation initiation	10.9		?	1108
51	Base plate hub assembly catalyst?	29.3	Defective tails	Essential	186, 249, 250, 264, 357, 540, 567, 821, 958, 1157; Szewczyk and Nieradko, personal communication
27	Base plate hub subunit	44.5	Defective tails; permit plating of fiberless phage	Essential	104, 186, 193, 249, 250, 264, 532, 1157, 1240
33	Protein connecting gp45 and gp55, to allow transcription by RNA polymerase from late promoters	12.8	No late RNA synthesis	Essential	97, 98, 109, 142, 264, 371, 404, 405, 436, 552, 786, 895, 1038, 1173, 1175, 1181, 1185, P. Williams, J. D. Mckinney, K. d'Acci, R. H. Drivdahl, C. Spaulding, J. Gleckler, and E. M. Kutter, unpublished data
dsbA	dsDNA binding protein	10.4	Facilitates some late RNA synthesis	Auxiliary	142, 303, 371, 372, 786, 995
rnh = das	RNase H; 5′ to 3′ DNase; yeast FEN homologue	35.6	Defective processing of Okazaki fragments; das mutations suppress T4 46, 47 and uvsX mutations	Auxiliary	41, 71, 72, 73, 142, 371, 372, 389, 402, 427, 429, 584, 731, 800, 826, 1139
34	Proximal tail fiber subunit	140.4	Fiberless particles	Essential	153, 217, 221, 248, 250, 264, 371, 391, 401, 538, 539, 920, 974, 1114a, 1148, 1190, 1187, 1189
oriG = ori34	DNA replication origin; primer transcript in opposite orientation of 34 transcript		No DNA synthesis from oriG	Auxiliary	55, 221, 573, 574, 577
35	Tail fiber hinge	40.1	Fiberless particles	Essential	153, 217, 248, 250, 264, 401, 538, 539, 920, 974, 1118, 1187, 1189, 1190
36	Small distal tail fiber subunit	23.3	Fiberless particles	Essential	153, 217, 248, 250, 264, 401, 538, 539, 840, 920, 1114a, 1187, 1189, 1190
37	Large distal tail fiber subunit	109.2	Fiberless particles, host range	Essential	153, 217, 248, 250, 264, 390, 391, 401, 538, 539, 745, 751, 752, 840, 920, 933, 934, 1023, 1067, 1070, 1114a, 1187, 1189, 1190
38	Assembly catalyst of distal tail fiber	22.3	Fiberless particles	Essential	217, 248, 250, 264, 390, 391, 401, 751, 920, 933, 1118, 1187, 1189, 1190
t = rV = stII	Holin, inner membrane pore protein, affects lysis timing and inhibition	25.2	Affect lysis by e lysozyme; suppress T4 rII and 63 mutations	Essential	2, 3, 4, 235, 374, 483, 583, 749, 851, 932
asiA	Protein that binds to host σ70, inhibits interaction with −35 regions of classical promoters, and facilitates interaction with T4 MotA protein	10.6	Defective middle mode, and (indirectly) late transcription	Almost essential	109, 177, 180, 419, 420, 425, 552, 610, 741, 786, 847, 848, 849, 852, 858, 977, 989, 1038-1040, 1043, 1103, 1104
arn	Inhibitor of MrcBC restriction nuclease	10.9		Auxiliary	140, 215; T. Djavakhishvili, N. Mzavia, A. Poglazov, and E. Kutter, unpublished data
motA = sip	Activator of middle promoters; dsDNA binding protein specific for mot boxes	23.6	Defective middle mode transcription; suppress rII-defects in λ lysogens; affects interaction with σ70 and AsiA	Almost essential	109, 156, 176, 177, 275, 276, 277, 293, 321, 375, 417, 419, 420, 430, 477, 552, 686, 692, 706, 773, 848, 963, 987, 1043, 1106, 1107, 1109
52	DNA topoisomerase subunit; membrane-associated protein	50.6	DNA delay	Essential; temperatures below 25°C; inhibition of host topoisomerase IV with novobiocin	184, 295, 296, 297, 445, 451, 432, 447, 571, 577, 654, 708, 801, 834, 941, 1037, 1047, 1059, 1216, 1236
ac	Membrane protein	5.5	Acriflavine resistant	Auxiliary	161, 861, 935, 999, 1143
ama = rs		5.4	Acriflavine resistant	Auxiliary	161, 894
stp	Peptide modulating host restriction system	3.18	Suppress pseT mutations	Auxiliary	161, 203, 204, 513, 514, 515, 859, 1021
ndd = D2b	Protein that disrupts host nucleoid; binds to host HU	16.9	Nucleoid disruption defective	Auxiliary; CT447	101, 102, 103, 161, 550, 551, 1016, 1017, 1018
pla262	Unknown			CT262	161, 204
denB	Endonuclease IV, single-strand-specific endonuclease	21.2	Allow progeny production of T4 with dC-containing DNA	Auxiliary	138, 140, 204, 1123; H. Krisch, personal communication; M. Saunders and K. Kreuter, personal communication
rIIB	Membrane-associated protein; affects host membrane ATPase	35.5	Rapid lysis; suppresses T4 30 and some 32 mutations	Auxiliary; rex+ λ lysogens; P2-like HK239 lysogen; tabR	2, 3, 4, 56, 59, 106, 121, 159, 181, 191, 224, 292, 293, 365, 441, 504, 503, 810, 834, 851, 874, 1021, 1059, 1160

^aGenes are listed by the currently used names, followed by alternative designations in the literature.

^bGene products processed into smaller peptides are indicated (∗) with the sizes or size range following the principal product.

^cBecause the distinction between “essential” and “nonessential” is not always obvious, when mutants have not been tested under all possible growth conditions or in all possible hosts, some “nonessential” genes are noted as “auxiliary.” Where known, restrictive hosts or plating conditions for mutant genes are noted.