FrzS Regulates Social Motility in Myxococcus xanthus by Controlling Exopolysaccharide Production

Abstract

Myxococcus xanthus Social (S) motility occurs at high cell densities and is powered by the extension and retraction of Type IV pili which bind ligands normally found in matrix exopolysaccharides (EPS). Previous studies showed that FrzS, a protein required for S-motility, is organized in polar clusters that show pole-to-pole translocation as cells reverse their direction of movement. Since the leading cell pole is the site of both the major FrzS cluster and type IV pilus extension/retraction, it was suggested that FrzS might regulate S-motility by activating pili at the leading cell pole. Here, we show that FrzS regulates EPS production, rather than type IV pilus function. We found that the frzS phenotype is distinct from that of Type IV pilus mutants such as pilA and pilT, but indistinguishable from EPS mutants, such as epsZ. Indeed, frzS mutants can be rescued by the addition of purified EPS, 1% methylcellulose, or co-culturing with wildtype cells. Our data also indicate that the cell density requirement in S-motility is likely a function of the ability of cells to construct functional multicellular clusters surrounding an EPS core.

Maintenance of Motility Bias during Cyanobacterial Phototaxis

“…S4 H). However, it remains unclear whether the lack of motility in this subpopulation is attributable to heterogeneities in pilus abundance (4,(12)(13)(14)22), cyclic AMP levels (19,22,36,37), the extracellular environment (11, 33,34,38,39), or other factors. Synechocystis cells responded rapidly (within minutes) to changes in light conditions by adjusting the distribution of step angles, with little to no memory about previous light conditions (Fig.…”

Myxococcus xanthus Developmental Cell Fate Production: Heterogeneous Accumulation of Developmental Regulatory Proteins and Reexamination of the Role of MazF in Developmental Lysis

“…We propose that this population be termed "cell clusters" to distinguish them from cells which are induced to aggregate into mounds during the developmental program (between 24 and 36 h). Although it has been recognized that cells in groups may have different molecular characteristics (2,28,51), most studies addressing the function of proteins involved in EPS production (e.g., Dif, FrzCD, or FibA) have been explored in isolated single-cell analyses or on the entire population of cells. Addressing these regulatory systems in cell groups is important for further understanding these regulatory systems.…”

PhpA, a tyrosine phosphatase of Myxococcus xanthus, is involved in the production of exopolysaccharide

“…Also, many other proteins are likely to play minor regulatory roles in M. xanthus EPS production (Berleman et al, 2011;Black et al, 2006;Dana & Shimkets, 1993;Kimura et al, 2004;Petters et al, 2012;Weimer et al, 1998). BY kinases have been found to phosphorylate heat shock sigma factors and single-stranded DNA-binding proteins other than enzymes involved in the synthesis of EPS.…”