TABLE 5.

Screening results of factors involved in zinc homeostasis for 179 porcine commensal E. coli.

			Distribution			Protein
			ZnCl2-MICs (μg/ml)
			128	256	512
Function	Symbol	Gene	n = 7a	n = 136a	n = 36a	L	AV	C	I	REF
			%	%	%	AA	n	%	%
Zinc uptake
Metal binding protein	ZinT	zinT	100	100	100	216	14	100	98.4	[1]
Zn-binding protein (ABC)	ZnuA	znuA	100	100	100	311	11	100	98.4	[2]
Integral subunit (ABC)	ZnuB	znuB	100	100	100	252	11	100	98.5	[2]
ATPase subunit (ABC)	ZnuC	znuC	100	100	100	261	5	100	99.0	[2]
Zn2+ uptake transporter	ZupT	zupT	100	100	100	257	2	100	99.6	[3]
Zn2+ uptake regulator	Zur	zur	100	100	100	172	10	100	96.4	[4]
Ammonia channel	AmtB	amtB	100	100	100	428	5	100	99.9	[5]
Put. arylsulfatase	AslA	aslA	100	100	100	552	11	100	98.5	[6]
OM channel	OmpC	ompC	100	100	100	368	10	100	90.8	[5]
Put. protein	YdfE	ydfE	100	100	100	255	19	100	96.1	[6]
Efflux protein (cysteine)	EamB	eamB	100	100	100	195	10	100	98.7	[5]
Efflux
AMG efflux pump	AcrD	acrD	100	100	100	1037	15	100	99.8	[7]
MDR transporter	MdtA	mdtA	100	100	100	415	20	100	99.2	[7]
MDR transporter	MdtB	mdtB	100	100	100	1040	24	100	98.1	[7]
MDR transporter	MdtC	mdtC	100	100	100	1025	24	100	98.0	[7]
MDR transporter	MdtD	mdtD	100	100	100	471	20	100	98.4	[7]
Ferrous-iron efflux pump	FieF	yiip	100	100	100	300	4	100	99.7	[8]
Metal transporter	ZitB	zitB	100	100	100	314	10	100	99.6	[9]
P1b-type ATPase	ZntA	zntA	100	100	100	732	13	100	97.4	[7]
Histidine-protein kinase	BaeS	baeS	100	100	100	467	10	100	94.3	[7]
Transcriptional regulator	BaeR	baeR	100	100	100	240	10	100	99.3	[7]
Transcriptional regulator	SoxS	soxS	100	100	100	108	8	100	99.5	[10]
Transcriptional activator	SoxR	soxR	100	100	100	154	8	100	99.5	[10]
Transcriptional regulator	ZntR	zntR	100	100	100	142	12	100	98.9	[11]
Transglycosylase E	EmtA	emtA	100	100	100	203	4	100	99.7	[6]
Formate dehydrogenase	FdnG	fdnG	100	100	100	1016	9	100	99.5	[6]
Put. Zn2+ protease	PqqL	pqqL	100	100	100	932	10	100	98.1	[12]
GTP cyclohydrolase II	RibA	ribA	100	100	100	197	7	100	99.8	[6]
Periplasmic chaperone	Spy	spy	100	100	100	159	9	100	99.7	[5]
Put. Zn2+ chaperone	YdaE	ydaE	42.9	16.2	52.8	57	3	100	85.0	[5]
Zn2+-stimulated GTPase	YeiR	yeiR	100	100	100	328	6	100	99.4	[13]
50S ribosomal protein	YkgM	ykgM	57.1	99.3	100	88	8	100	98.4	[14]
Zn2+ resistance as. protein	ZraP	zraP	100	100	100	142	11	100	98.0	[5]
Transcriptional regulator	ZraR	zraR	100	100	100	441	17	100	99.2	[15]
Sensor protein	ZraS	zraS	100	100	100	441	15	100	98.5	[15]

All 179 porcine commensal E. coli were screened with respect to the presence or absence of 35 factors involved in zinc homeostasis as described before. Predicted amino acid sequence lengths were compared to those of E. coli K-12 MG1655 in order to check for putative premature stop codons or deletions affecting the putative function of the protein. None of the amino acid sequence variations (AV) was solely associated with a particular ZnCl₂ MIC. Amino acid sequence variation among the isolate collection primarily reflects the isolate’s genetic backgrounds. Put., putative; OM, outer membrane; MDR, multidrug resistance; AMG, aminoglycoside; as., associated; n, number of isolates; ^a, number of isolates with particular ZnCl₂ MIC; L, length; AA, amino acid sequence; AV, number of amino acid sequence variants; C, amino acid sequence coverage with respect to reference protein in E. coli K-12 MG1655; I, maximum amino acid sequence identity among the 179 isolates; REF, references. [1] Colaço et al., 2016; [2] Yatsunyk et al., 2008; [3] Grass et al., 2005; [4] Choi et al., 2017; [5] Lee et al., 2005; [6] Graham et al., 2009; [7] Wang and Fierke, 2013; [8] Lu et al., 2009; [9] Watly et al., 2016; [10] Warner and Levy, 2012; [11] Wang et al., 2012; [12] Subashchandrabose et al., 2013; [13] Blaby-Haas et al., 2012; [14] Hensley et al., 2012; [15] Petit-Hartlein et al., 2015.