Figure 1
From: Agr Quorum Sensing influences the Wood-Ljungdahl pathway in Clostridium autoethanogenum
Schematic of the proposed Agr QS systems in C. autoethanogenum. Two separate, putative agr operons are present in the genome. Both are incomplete: operon 1 is missing the response regulator encoding gene agrA, whereas operon 2 is lacking both agrB1 and agrA homologs. The precursors of two distinct autoinducing peptides (AIPs) are encoded by agrD1 and agrD2, respectively. Export and processing of both precursors is hypothesised to be mediated by membrane associated AgrB1. AgrC1 and AgrC2 are putative histidine kinases which act as receptors for AgrD1 and AgrD2 derived AIPs, respectively. In other Agr systems, their role is to phosphorylate their cognate AgrA response regulators. In C. autoethanogenum, these may be encoded elsewhere on the chromosome. A spo0E-like gene (CLAU_0813) is located downstream of agrB1, this arrangement is also observed in several other acetogenic clostridia.
