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Endogenous nitric oxide regulates the recovery of the radiation-resistant bacterium Deinococcus radiodurans from exposure to UV light.

ABSTRACT: Deinococcus radiodurans (Dr) withstands desiccation, reactive oxygen species, and doses of radiation that would be lethal to most organisms. Deletion of a gene encoding a homolog of mammalian nitric oxide synthase (NOS) severely compromises the recovery of Dr from ultraviolet (UV) radiation damage. The Deltanos defect can be complemented with recombinant NOS, rescued by exogenous nitric oxide (NO) and mimicked in the wild-type strain with an NO scavenging compound. UV radiation induces both upregulation of the nos gene and cellular NO production on similar time scales. Growth recovery does not depend on NO being present during UV irradiation, but rather can be manifested by NO addition hours after exposure. Surprisingly, nos deletion does not increase sensitivity to oxidative damage, and hydrogen peroxide does not induce nos expression. However, NOS-derived NO upregulates transcription of obgE, a gene involved in bacterial growth proliferation and stress response. Overexpression of the ObgE GTPase in the Deltanos background substantially alleviates the growth defect after radiation damage. Thus, NO acts as a signal for the transcriptional regulation of growth in D. radiodurans.

SUBMITTER: Patel BA

PROVIDER: S-EPMC2775278 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature

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Endogenous nitric oxide regulates the recovery of the radiation-resistant bacterium Deinococcus radiodurans from exposure to UV light.

Patel Bhumit A BA Moreau Magali M Widom Joanne J Chen Huan H Yin Longfei L Hua Yuejin Y Crane Brian R BR

Proceedings of the National Academy of Sciences of the United States of America 20091019 43

Deinococcus radiodurans (Dr) withstands desiccation, reactive oxygen species, and doses of radiation that would be lethal to most organisms. Deletion of a gene encoding a homolog of mammalian nitric oxide synthase (NOS) severely compromises the recovery of Dr from ultraviolet (UV) radiation damage. The Deltanos defect can be complemented with recombinant NOS, rescued by exogenous nitric oxide (NO) and mimicked in the wild-type strain with an NO scavenging compound. UV radiation induces both upre ...[more]

PMID: 19841256

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Project description:Environmental DNA uptake by certain bacteria and its integration into their genome create genetic diversity and new phenotypes. DNA processing protein A (DprA) is part of a multiprotein complex and facilitates the natural transformation (NT) phenotype in most bacteria. Deinococcus radiodurans, an extremely radioresistant bacterium, is efficient in NT, and its genome encodes nearly all of the components of the natural competence complex. Here, we have characterized the DprA protein of this bacterium (DrDprA) for the known characteristics of DprA proteins of other bacteria and the mechanisms underlying the DNA-RecA interaction. DrDprA has three domains. In vitro studies showed that purified recombinant DrDprA binds to both single-strand DNA (ssDNA) and double-strand DNA (dsDNA) and is able to protect ssDNA from nucleolytic degradation. DrDprA showed a strong interaction with DrRecA and facilitated RecA-catalyzed functions in vivo. Mutational studies identified DrDprA amino acid residues crucial for oligomerization, the interaction with DrRecA, and DNA binding. Furthermore, we showed that both oligomerization and DNA binding properties of DrDprA are integral to its support of the DrRecA-catalyzed strand exchange reaction (SER) in vitro. Together, these data suggested that DrDprA is largely structurally conserved with other DprA homologs but shows some unique structure-function features like the existence of an additional C-terminal Drosophila melanogaster Miasto-like protein 1 (DML1) domain, equal affinities for ssDNA and dsDNA, and the collective roles of oligomerization and DNA binding properties in supporting DrRecA functions. IMPORTANCE Bacteria can take up extracellular DNA (eDNA) by natural transformation (NT). Many bacteria, including Deinococcus radiodurans, have constitutive competence systems and can take up eDNA throughout their growth phase. DprA (DNA processing protein A) is a transformation-specific recombination mediator protein (RMP) that plays a role in bacterial NT, and the absence of this gene significantly reduces the transformation efficiencies of both chromosomal and plasmid DNA. NT helps bacteria survive under adverse conditions and contributes to genetic diversity in bacteria. The present work describes the characterization of DprA from D. radiodurans and will add to the existing knowledge of DprA biology.

Dataset Information

Endogenous nitric oxide regulates the recovery of the radiation-resistant bacterium Deinococcus radiodurans from exposure to UV light.

Publications

Endogenous nitric oxide regulates the recovery of the radiation-resistant bacterium Deinococcus radiodurans from exposure to UV light.

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