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H‐NOX regulation of c‐di‐GMP metabolism and biofilm formation in Legionella pneumophila
Author(s) -
Carlson Hans K.,
Vance Russell E.,
Marletta Michael A.
Publication year - 2010
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2010.07259.x
Subject(s) - biofilm , legionella pneumophila , biology , microbiology and biotechnology , phenotype , gene , biochemistry , bacteria , genetics
Summary 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. In summary: (i) unmarked deletions in the hnox1 gene do not affect growth rate in liquid culture or replication in permissive macrophages; (ii) the Δ hnox1 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 Δ hnox1 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.