H-NOX regulation of c-di-GMP metabolism and biofilm formation in Legionella pneumophila.
Haem Nitric oxide/OXygen (H-NOX) binding domains are a family of haemoprotein sensors that are widespread in bacterial genomes, but limited information is available on their function. Legionella pneumophila is the only prokaryote found, thus far, to encode two H-NOX proteins. This paper presents data supporting a role for one of the L. pneumophila H-NOXs in the regulation of biofilm formation.


CONCLUSIONS
(i) unmarked deletions in the hnox1 gene do not affect growth rate in liquid culture or replication in permissive macrophages; (ii) the Δhnox1 strain displays a hyper-biofilm phenotype; (iii) the gene adjacent to hnox1 is a GGDEF-EAL protein, lpg1057, and overexpression in L. pneumophila of this protein, or the well-studied diguanylate cyclase, vca0956, results in a hyper-biofilm phenotype; (iv) the Lpg1057 protein displays diguanylate cyclase activity in vitro and this activity is inhibited by the Hnox1 protein in the Fe(II)-NO ligation state, but not the Fe(II) unligated state; and (v) consistent with the Hnox1 regulation of Lpg1057, unmarked deletions of lpg1057 in the Δhnox1 background results in reversion of the hyper-biofilm phenotype back to wild-type biofilm levels. Taken together, these results suggest a role for hnox1 in regulating c-di-GMP production by lpg1057 and biofilm formation in response to NO.
Carlson
Hans K
HK
Departments of ChemistryMolecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
Vance
Russell E
RE
Departments of ChemistryMolecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
Marletta
Michael A
MA
Departments of ChemistryMolecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D018441:Biofilms / Q000254:growth & development*; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D016952:Legionella pneumophila / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism
D001426:Bacterial Proteins; D009569:Nitric Oxide; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP