Identification of Bacillus subtilis SipW as a bifunctional signal peptidase that controls surface-adhered biofilm formation.
Biofilms of microbial cells encased in an exopolymeric matrix can form on solid surfaces, but how bacteria sense a solid surface and upregulate biofilm genes is largely unknown. We investigated the role of the Bacillus subtilis signal peptidase, SipW, which has a unique role in forming biofilms on a solid surface and is not required at an air-liquid interface. Surprisingly, we found that the signal peptidase activity of SipW was not required for solid-surface biofilms. Furthermore, a SipW mutant protein was constructed that lacks the ability to form a solid-surface biofilm but still retains signal peptidase activity. Through genetic and gene expression tests, the non-signal peptidase role of SipW was found to activate biofilm matrix genes specifically when cells were on a solid surface. These data provide the first evidence that a signal peptidase is bifunctional and that SipW has a regulatory role in addition to its role as a signal peptidase.
Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA.
Rebecca
R
Terra
Nicola R
NR
Stanley-Wall
Guoqiang
G
Cao
Beth A
BA
Lazazzera
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D018441:Biofilms; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D008565:Membrane Proteins; D012697:Serine Endopeptidases; C026515:type I signal peptidase