An Adenylyl Cyclase, CyaA, of Myxococcus xanthus Functions in Signal Transduction during Osmotic Stress

AUTOR(ES)

Kimura, Yoshio

FONTE

American Society for Microbiology

RESUMO

An adenylyl cyclase gene (cyaA) present upstream of an osmosensor protein gene (mokA) was isolated from Myxococcus xanthus. cyaA encoded a polypeptide of 843 amino acids with a predicted molecular mass of 91,187 Da. The predicted cyaA gene product had structural similarity to the receptor-type adenylyl cyclases that are composed of an amino-terminal sensor domain and a carboxy-terminal catalytic domain of adenylyl cyclase. In reverse transcriptase PCR experiments, the transcript of the cyaA gene was detected mainly during development and spore germination. A cyaA mutant, generated by gene disruption, showed normal growth, development, and germination. However, a cyaA mutant placed under conditions of ionic (NaCl) or nonionic (sucrose) osmostress exhibited a marked reduction in spore formation and spore germination. When wild-type and cyaA mutant cells at developmental stages were stimulated with 0.2 M NaCl or sucrose, the mutant cells increased cyclic AMP accumulation at levels similar to those of the wild-type cells. In contrast, the mutant cells during spore germination had mainly lost the ability to respond to high-ionic osmolarity. In vegetative cells, the cyaA mutant responded normally to osmotic stress. These results suggested that M. xanthus CyaA functions mainly as an ionic osmosensor during spore germination and that CyaA is also required for osmotic tolerance in fruiting formation and sporulation.

Documentos Relacionados

• Two amino acid substitutions convert a guanylyl cyclase, RetGC-1, into an adenylyl cyclase
• Targeted mutations that ablate either the adenylate cyclase or hemolysin function of the bifunctional cyaA toxin of Bordetella pertussis abolish virulence.
• The Myxococcus xanthus asgA gene encodes a novel signal transduction protein required for multicellular development.
• The cyanobacterial tandem GAF domains from the cyaB2 adenylyl cyclase signal via both cAMP-binding sites
• Adenylyl cyclase type 5 protein expression during cardiac development and stress