ESCHERICHIA-COLI AND OTHER SPECIES OF THE ENTEROBACTERIACEAE ENCODE APROTEIN SIMILAR TO THE FAMILY OF MIP-LIKE FK506-BINDING PROTEINS

A newly identified gene in Escherichia coli, fkpA, encodes a protein w ith extensive similarity to the macrophage infectivity potentiator (Mi p) proteins of Legionella pneumophila and Chlamydia trachomatis. The F kpA protein may be a new member of the family of FK506-binding protein s (FKBPs) because its carboxyl domain includes a sequence that matches the consensus FK506-binding motif in 40 of 48 positions, including th ose amino acids at the active site that form hydrogen bonds with the d rug FK506. The amino acid sequence of the 29kDa FkpA protein is 30-35% identical to the Mip proteins of L. pneumophila, L. micdadei, and C. trachomatis. Of the 270 amino acids of FkpA, 113 (42%) are identical t o the sequence of one or another of these Mip proteins. Overexpression of FkpA or deletion of fkpA from the E. coli chromosome had no detrim ental effect on bacterial growth, indicating that fkpA is not an essen tial gene. Hybridization of fkpA-specific DNA probes to genomic blots revealed that similar genes exist in several representatives of the En terobacteriaceae. Thus, mip-like genes are not found exclusively in ba cteria having a predominately intracellular life style, but instead ap pear to be a new FKBP subfamily that is a common constituent of many b acteria.