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The orphan response regulator DigR is required for synthesis of extracellular matrix fibrils in Myxococcus xanthus

ABSTRACT: In Myxococcus xanthus, two component systems have crucial roles in regulating motility behavior and development. Here, we describe an orphan response regulator consisting of an N-terminal receiver domain and a C-terminal DNA binding domain, which is required for A- and type IV pili dependent gliding motility. Genetic evidence suggests that phosphorylation of the conserved, phosphorylatable aspartate residue in the receiver domain is required for DigR activity. Consistent with the defect in type IV pili dependent motility, a digR mutant is slightly reduced in type IV pili biosynthesis and the composition of the extracellular matrix fibrils is abnormal with an increased content of polysaccharides and decreased accumulation of the FibA metalloprotease. Using genome-wide transcriptional profiling, 118 genes were identified that are directly or indirectly regulated by DigR. These genes only include two genes, agmQ and cheY4, previously implicated in A- and type IV pili dependent motility, respectively. In silico analyses showed that 36% of the differentially expressed genes are likely to encode exported proteins. Moreover, four genes encoding homologs of ECF sigma factors, which typically control aspects of cell envelope homeostasis, are differentially expressed in a digR mutant. We suggest that the DigR response regulator has an important function in cell envelope homeostasis and that the motility defects in a digR mutant are instigated by the abnormal cell envelope and abnormal expression of agmQ and cheY4. Keywords: vegetative analysis (delta)DigR / DK1622 (wt)

ORGANISM(S): Myxococcus xanthus

PROVIDER: GSE9501 | GEO | 2007/11/02

SECONDARY ACCESSION(S): PRJNA103293

REPOSITORIES: GEO

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