Two forms of phosphomannomutase in gammaproteobacteria: The overlooked membrane‐bound form of AlgC is required for twitching motility of Lysobacter enzymogenes

Abstract

Summary Lysobacter enzymogenes, a member of Xanthomonadaceae, is a promising tool to control crop‐destroying fungal pathogens. One of its key antifungal virulence factors is the type IV pili that are required for twitching motility. Transposon mutagenesis of L. enzymogenes revealed that the production of type IV pili required the presence of the Le2152 gene, which encodes an AlgC‐type phosphomannomutase/phosphoglucomutase (PMM). However, in addition to the cytoplasmic PMM domain, the Le2152 gene product contains a ~200‐aa N‐terminal periplasmic domain that is anchored in the membrane by two transmembrane segments and belongs to the dCache superfamily of periplasmic sensor domains. Sequence analysis identified similar membrane‐anchored PMMs, encoded in conserved coaBC‐dut‐algC gene clusters, in a variety of gammaproteobacteria, either as the sole PMM gene in the entire genome or in addition to the gene encoding the stand‐alone enzymatic domain. Previously overlooked N‐terminal periplasmic sensor domains were detected in the well‐characterized PMMs of Pseudomonas aeruginosa and Xanthomonas campestris, albeit not in the enzymes from Pseudomonas fluorescens, Pseudomonas putida or Azotobacter vinelandii. It appears that after the initial cloning of the enzymatically active soluble part of P. aeruginosa AlgC in 1991, all subsequent studies utilized N‐terminally truncated open reading frames. The N‐terminal dCache sensor domain of AlgC is predicted to modulate the PMM activity of the cytoplasmic domain in response to as yet unidentified environmental signal(s). AlgC‐like membrane‐bound PMMs appear to comprise yet another environmental signalling system that regulates the production of type IV pili and potentially other systems in certain gammaproteobacteria.

Isolation, identification, and biochemical characterization of a novel bifunctional phosphomannomutase/phosphoglucomutase from the metagenome of the brown alga Laminaria digitata

“…Frontiers in Microbiology 09 frontiersin.org a-d-glucose-1-phosphate (Glu1P) produced by both cellobiose phosphorylase and by the Leloir pathway, into d-glucose 6-phosphate (Glu6P), which then enters the glycolytic pathway (Kampik et al, 2021). Apart from their involvement in carbohydrate metabolism in bacteria, PMM/PGMs have also been shown to have other quite diverse roles with an AlgC-type PMM activity being shown to be involved in the production of type IV pili and linked to twitching mobility in Lysobacter enzymogenes (Qian et al, 2019); while PGM activity in the citrus canker causing bacterium Xanthomonas citri is required for the synthesis of precursors of the pathogenesis-related polysaccharide xanthan (Goto et al, 2016). PGM activity has also been shown to be involved in normal cell growth and morphology, together with biofilm formation in B. subtilis (Lazarevic et al, 2005).…”