SwrAA activates poly-gamma-glutamate synthesis in addition to swarming in Bacillus subtilis.
Poly-gamma-glutamic acid (gamma-PGA) is an extracellular polymer produced by various strains of Bacillus. Iotat was first described as the component of the capsule in Bacillus anthracis, where it plays a relevant role in virulence. gamma-PGA is also a distinctive component of 'natto', a traditional Japanese food consisting of soybean fermented by Bacillus subtilis (natto). Domesticated B. subtilis strains do not synthesize gamma-PGA although they possess the functional biosynthetic pgs operon. In the present work we explore the correlation between the genetic determinants, swrAA and degU, which allow a derivative of the domestic strain JH642 to display a mucoid colony morphology on LB agar plates due to the production of gamma-PGA. Full activation of the pgs operon requires the co-presence of SwrAA and the phosphorylated form of DegU (DegU approximately P). The presence of either DegU approximately P or SwrAA alone has only marginal effects on pgs operon transcription and gamma-PGA production. Although SwrAA was identified as necessary for swarming and full swimming motility together with DegU, we show that motility is not involved in gamma-PGA production. Activation of gamma-PGA synthesis is therefore a motility-independent phenotype in which SwrAA and DegU approximately P display a cooperative effect.
Osera
Cecilia
C
Dipartimento di Genetica e Microbiologia, Università degli Studi di Pavia, via Ferrata 1, 27100 Pavia, Italy.
Amati
Giuseppe
G
Dipartimento di Genetica e Microbiologia, Università degli Studi di Pavia, via Ferrata 1, 27100 Pavia, Italy.
Calvio
Cinzia
C
Dipartimento di Genetica e Microbiologia, Università degli Studi di Pavia, via Ferrata 1, 27100 Pavia, Italy.
Galizzi
Alessandro
A
Dipartimento di Genetica e Microbiologia, Università degli Studi di Pavia, via Ferrata 1, 27100 Pavia, Italy.
D001412:Bacillus subtilis / Q000502:physiology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D010766:Phosphorylation; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000096:biosynthesis; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
D001426:Bacterial Proteins; C066497:DegU protein, Bacteria; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid