Document Detail


Purification and spectroscopic characterization of Ctb, a group III truncated hemoglobin implicated in oxygen metabolism in the food-borne pathogen Campylobacter jejuni.
MedLine Citation:
PMID:  16681372     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Campylobacter jejuni is a food-borne bacterial pathogen that possesses two distinct hemoglobins, encoded by the ctb and cgb genes. The former codes for a truncated hemoglobin (Ctb) in group III, an assemblage of uncharacterized globins in diverse clinically and technologically significant bacteria. Here, we show that Ctb purifies as a monomeric, predominantly oxygenated species. Optical spectra of ferric, ferrous, O(2)- and CO-bound forms resemble those of other hemoglobins. However, resonance Raman analysis shows Ctb to have an atypical nu(Fe)(-)(CO) stretching mode at 514 cm(-)(1), compared to those of the other truncated hemoglobins that have been characterized so far. This implies unique roles in ligand stabilization for TyrB10, HisE7, and TrpG8, residues highly conserved within group III truncated hemoglobins. Because C. jejuni is a microaerophile, and a ctb mutant exhibits O(2)-dependent growth defects, one of the hypothesized roles of Ctb is in the detoxification, sequestration, or transfer of O(2). The midpoint potential (E(h)) of Ctb was found to be -33 mV, but no evidence was obtained in vitro to support the hypothesis that Ctb is reducible by NADH or NADPH. This truncated hemoglobin may function in the facilitation of O(2) transfer to one of the terminal oxidases of C. jejuni or, instead, facilitate O(2) transfer to Cgb for NO detoxification.
Authors:
Laura M Wainwright; Yinghua Wang; Simon F Park; Syun-Ru Yeh; Robert K Poole
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochemistry     Volume:  45     ISSN:  0006-2960     ISO Abbreviation:  Biochemistry     Publication Date:  2006 May 
Date Detail:
Created Date:  2006-05-09     Completed Date:  2006-08-08     Revised Date:  2013-06-07    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  United States    
Other Details:
Languages:  eng     Pagination:  6003-11     Citation Subset:  IM    
Affiliation:
Department of Molecular Biology and Biotechnology, The University of Sheffield, UK.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Sequence
Base Sequence
Campylobacter jejuni / metabolism*
DNA Primers
Hemoglobins / chemistry,  isolation & purification*,  metabolism
Molecular Sequence Data
Oxygen / metabolism*
Sequence Homology, Amino Acid
Spectrum Analysis, Raman
Truncated Hemoglobins
Grant Support
ID/Acronym/Agency:
HL65465/HL/NHLBI NIH HHS; R01 HL065465-04/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/DNA Primers; 0/Hemoglobins; 0/Truncated Hemoglobins; 7782-44-7/Oxygen
Comments/Corrections

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