TABLE 1.

Characteristics, reporter protein fusion assay results, and assigned export pathway for each putative Tat signal peptide

Signal peptide	Sequencea	Hydro- phobicity, h-regionb	Charge, c-region	Charge, mature N terminus	Charge, net (cleavage area)	GFP-SsrA FACS mean fluorescencec		PhoA activityd	MBP plate growthe		Export pathway
						WT	tatC		WT	TatC
								%
FdnG	MDVSRRQFFKICAGGMAGTTVAALGFAPKQALAQARNYKL	2.25	+1	+2	+3	2	3	n.e.	+	−	Tat
FdoG	MQVSRRQFFKICAGGMAGTTAAALGFAPSVALAETRQYKL	1.91	0	+1	+1	2	4	n.e.	+	−	Tat
NapG	MSRSAKPQNGRRRFLRDVVRTAGGLAAVGVALGLQQQTARASGVRLR	2.00	+1	+2	+3	2	2	n.e.	+	−	Tat
NrfC	MTWSRRQFLTGVGVLAAVSGTAGRVVAKTLNIN	2.28	+1	+1	+2	9	3	n.e.	+	−	Tat
HyaA	MNNEETFYQAMRRQGVTRRSFLKYCSLAATSLGLGAGMAPKIAWALENKPR	1.36	+1	+1	+2	27	3	0	+	−	Tat
YnfE	MSKNERMVGISRRTLVKSTAIGSLALAAGGFSLPFTLRNAAAAVQQAREK	2.01	+1	+1	+2	9	3	0	+	−	Tat
WcaM	MPFKKLSRRTFLTASSALAFLHTPFARALPARQS	1.82	+1	+1	+2	13	3	1	+	−	Tat
TorA	MNNNDLFQASRRRFLAQLGGLTVAGMLGPSLLTPRRATAAQAATDA	1.42	+2	−1	+1	90	2	2	+	−	Tat
NapA	MKLSRRSFMKANAVAAAAAAAGLSVPGVARAVVGQ	1.53	+1	0	+1	2	3	3	+	−	Tat
YagT	MSNQGEYPEDNRVGKHEPHDLSLTRRDLIKVSAATAATAVVYPHSTLAASVPAA	1.63	0	0	0	57	5	3	+	−	Tat
YcbK	MDKFDANRRKLLALGGVALGAAILPTPAFATLSTPR	2.40	0	+1	+1	82	4	3	+	−	Tat
DmsA	MKTKIPDAVLAAEVSRRGLVKTTAIGGLAMASSALTLPFSRIAHAVDSAIP	1.56	+1	−1	0	90	6	2	+	+	Tat+Sec
YdhX	MSWIGWTVAATALGDNQMSFTRRKFVLGMGTVIFFTGSASSLLANTRQEK	2.31	0	+1	+1	7	5	2	+	+	Tat+Secf
YahJ	MKESNSRREFLSQSGKMVTAAALFGTSVPLAHAAVAGTL	2.17	0	0	0	100	6	3	+	+	Tat+Sec
YedY	MKKNQFLKESDVTAESVFFMKRRQVLKALGISATALSLPHAAHADLLSWF	1.73	0	−1	−1	47	6	4	+	+	Tat+Sec
CueO	MQRRDFLKYSVALGVASALPLWSRAVFAAERPTL	1.79	+1	0	+1	21	4	5	+	+	Tat+Sec
SufI	MSLSRRQFIQASGIALCAGAVPLKASAAGQQQP	1.74	+1	0	+1	29	2	5	+	+	Tat+Sec
YcdB	MQYKDENGVNEPSRRRLLKVIGALALAGSCPVAHAQKTQSA	2.66	0	+1	+1	123	5	6	+	+	Tat+Sec
TorZ	MIREEVMTLTRREFIKHSGIAAGALVVTSAAPLPAWAEEKGGK	1.98	0	0	0	56	4	6	+	+	Tat+Sec
HybA	MNRRNFIKAASCGALLTGALPSVSHAAAENRPP	1.98	0	0	0	33	3	11	+	+	Tat+Sec
YnfF	MMKIHTTEALMKAEISRRSLMKTSALGSLALASSAFTLPFSQMVRAAEAPVE	1.55	+1	−2	−1	49	5	15	+	+	Tat+Sec
HybO	MTGDNTLIHSHGINRRDFMKLCAALAATMGLSSKAAAEMAESV	2.47	+1	−2	−1	28	3	17	+	+	Tat+Sec
AmiC	MSGSNTAISRRRLLQGAGAMWLLSVSQVSLAAVSQVV	1.40	0	0	0	36	9	18	+	+	Tat+Sec
AmiA	MSTFKPLKTLTSRRQVLKAGLAALTLSGMSQAIAKDELLK	2.10	0	0	0	22	2	79	+	+	Tat+Sec
YfhG	MRHIFQRLLPRRLWLAGLPCLALLGCVQNHNKPAIDT	2.16	0	0	0	21	5	93	+	+	Tat+Sec
MdoD	MDRRRFIKGSMAMAAVCGTSGIASLFSQAAFAADSDIA	2.42	0	−2	−2	15	5	165	+	+	Tat+Sec
FhuD	MSGLPLISRRRLLTAMALSPLLWQMNTAHAAAIDPN	1.70	0	−1	−1	6	2	256	+	+	Tat+Secf
YaeI	MISRRRFLQATAATIATSSGFGYMHYCEPGWFELIRHRLAFFKDNAAPFKIL	2.80	0	+1	+1	2	2	20	+	+	Sec
YcdO	MTINFRRNALQLSVAALFSSAFMANAADVPQVK	1.63	0	0	0	5	4	107	+	+	Sec

^aShown in bold is the signal peptide c-region and in italics the predicted N-terminal region of the mature protein.

^bAverage hydrophobicity using Kyte Doolittle values is calculated for the h-region, defined as described by Cristóbal et al. (9).

^cSignal peptide-GFP-SsrA fusions were expressed both in wild type and tatC strains, and whole cell fluorescence values were measured by flow cytometry (fluorescence-activated cell sorter). The average mean fluorescence values of at least three replicate experiments are shown.

^dActivity of whole cell lysates of a phoAR strain expressing each signal peptide-PhoA fusion as percentage of activity of PhoA with its own signal peptide. FACS, fluorescence-activated cell sorter; n.e., no expression detected.

^eColonies present (+) or absent (−) after 2 days at 37 °C on maltose minimal medium plates in malE (WT) and malE tatC (ΔtatC) strains. For ssDmsA and ssSufI, colonies appeared after 3 days in the ΔtatC strain.

^fTat portion of assignment based on epitope tagging for ssYdhX and on the results of Ize et al. (18) for ssFhuD; Sec portion of assignment based on reporter fusion results for both ssYdhX and ssFhuD.