Table 2.

Comparison of Salmonella Iro proteins with E. coli Iro proteins and proteins involved in microcin biosynthesis

iro gene from Salmonella	Homologs	Size of gene product, aa	Putative or demonstrated* function of the proteins	% Amino acid identity
iroB		371	Glycosyltransferase
	iroB E. coli 536	371	Glycosyltransferase	72
	mceC Klebsiella pneumoniae	370	Maturation of microcin E492	77
	mcmL E. coli	372	Maturation of microcins M and H	72
	snoG Streptomyces  nogalater	390	Glycosyltransferase*	33
iroC		1,261	ABC exporter
	iroC E. coli 536	1,218	ABC exporter	76
	SCO2763 Streptomyces  coelicolor	1,243	ABC transporter	39
	MDR1 Homo sapiens	1,280	ABC exporter, multidrug resistance protein 1*	28
iroD		409	Similar to enterochelin esterase
	iroD E. coli 536	414	Similar to enterochelin esterase	68
	mceD K. pneumoniae	414	Maturation of microcin E492	56
	mcmK E. coli	424	Maturation of microcins M and H	55
	fes E. coli	374	Enterochelin esterase*	27
iroE		318	Periplasmic hydrolase
	iroE E. coli 536	311	Periplasmic hydrolase	61
	AMY3E Oryza sativa	437	Alpha-amylase isozyme 3E*	26
iroN		725	Catecholate siderophore receptor*
	iroN E. coli 536	726	Catecholate siderophore receptor*	82
	fepA E. coli	746	Enterochelin receptor*	52
	cir E. coli	663	DHBS-catecholate siderophore receptor*	33
	fiu E. coli	760	DHBS-catecholate siderophore receptor*	22

The similarity to some better-defined homologs and the percent identity are given. 

^*Proteins for which experimental evidence for the function is available.