Structural basis for the regulation of chemotaxis by MapZ in the presence of c‐di‐GMP

摘要

The bacterial second messenger cyclic diguanylate monophosphate (c‐di‐GMP) mediates multiple aspects of bacterial physiology through binding to various effectors. In some cases, these effectors are single‐domain proteins which only contain a PilZ domain. It remains largely unknown how single‐domain PilZ proteins function and regulate their downstream targets. Recently, a single‐domain PilZ protein, MapZ (PA4608), was identified to inhibit the activity of the methyltransferase CheR1. Here, crystal structures of the C‐terminal domain of CheR1 containing SAH and of CheR1 in complex with c‐di‐GMP‐bound MapZ are reported. It was observed that the binding site of MapZ in CheR1 partially overlaps with the SAH/SAM‐binding pocket. Consequently, binding of MapZ blocks SAH/SAM binding. This provides direct structural evidence on the mechanism of inhibition of CheR1 by MapZ in the presence of c‐di‐GMP.