TABLE 3.

Typical gene clusters containing HPr-like proteins in the phyla Firmicutes and Proteobacteria^a

Phylum	Gene cluster containing:
	HPr	NPr	Crh	SPr	XPrb
Firmicutes	H-I, H		j-k-l-H
Proteobacteria
α	H-I				N-h-IIA∥K′-(j)-IIA-H-(I)
β					(N)-(h)-IIA-K-j∥IIA-H-I
γ	H-I-IIA	N-h-IIA-j-H		IIA-IIB-IIC-sk-H	N-h-(IIA)-K-j-IIA-H-I
δ					N-h-K-j-IIA-H-I

^aSPr and XPr are defined in the text. Symbols used are as follows: H, HPr-like protein; N, σ^N transcription factor; I, PTS enzyme I; IIA, IIB, and IIC, PTS enzymes IIA, IIB, and IIC; K and K′, full-length and short-version HPrK/P homologues, respectively; j, k, l, and h, unknown conserved genes; sk, putative sugar kinase.

^bSubclusters left and right of ∥ are distantly located on the genomes. Parentheses indicate that the genes are not present in all species.