Premium
Nitrosative stress sensing in Porphyromonas gingivalis : structure of and heme binding by the transcriptional regulator HcpR
Author(s) -
Belvin B. Ross,
Musayev Faik N.,
Burgner John,
Scarsdale J. Neel,
Escalante Carlos R.,
Lewis Janina P.
Publication year - 2019
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.374
H-Index - 138
ISSN - 2059-7983
DOI - 10.1107/s205979831900264x
Subject(s) - porphyromonas gingivalis , regulator , heme , chemistry , hexacoordinate , biophysics , response regulator , crystallography , nitric oxide , biochemistry , bacteria , stereochemistry , biology , bacterial protein , genetics , organic chemistry , enzyme , silicon , gene
Although the HcpR regulator plays a vital step in initiation of the nitrosative stress response in many Gram‐negative anaerobic bacteria, the molecular mechanisms that it uses to mediate gas sensing are not well understood. Here, a 2.6 Å resolution crystal structure of the N‐terminal sensing domain of the anaerobic periodontopathogen Porphyromonas gingivalis HcpR is presented. The protein has classical features of the regulators belonging to the FNR‐CRP family and contains a hydrophobic pocket in its N‐terminal sensing domain. It is shown that heme bound to HcpR exhibits heme iron as a hexacoordinate system in the absence of nitric oxide (NO) and that upon nitrosylation it transitions to a pentacoordinate system. Finally, small‐angle X‐ray scattering experiments on full‐length HcpR reveal that the C‐terminal DNA‐binding domain of HcpR has a high degree of interdomain flexibility.