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Title: Structures of Arg- and Gln-type bacterial cysteine dioxygenase homologs: Arg- and Gln-type Bacterial CDO Homologs

In some bacteria, cysteine is converted to cysteine sulfinic acid by cysteine dioxygenases (CDO) that are only ~15–30% identical in sequence to mammalian CDOs. Among bacterial proteins having this range of sequence similarity to mammalian CDO are some that conserve an active site Arg residue (“Arg-type” enzymes) and some having a Gln substituted for this Arg (“Gln-type” enzymes). Here, we describe a structure from each of these enzyme types by analyzing structures originally solved by structural genomics groups but not published: a Bacillus subtilis “Arg-type” enzyme that has cysteine dioxygenase activity (BsCDO), and a Ralstonia eutropha “Gln-type” CDO homolog of uncharacterized activity (ReCDOhom). The BsCDO active site is well conserved with mammalian CDO, and a cysteine complex captured in the active site confirms that the cysteine binding mode is also similar. The ReCDOhom structure reveals a new active site Arg residue that is hydrogen bonding to an iron-bound diatomic molecule we have interpreted as dioxygen. Notably, the Arg position is not compatible with the mode of Cys binding seen in both rat CDO and BsCDO. As sequence alignments show that this newly discovered active site Arg is well conserved among “Gln-type” CDO enzymes, we conclude that the “Gln-type” CDO homologsmore » are not authentic CDOs but will have substrate specificity more similar to 3-mercaptopropionate dioxygenases.« less
Authors:
 [1] ;  [1] ;  [1]
  1. Oregon State Univ., Corvallis, OR (United States). Dept. of Biochemistry and Biophysics
Publication Date:
OSTI Identifier:
1179449
Grant/Contract Number:
AC02-98CH10886; DK-056649
Type:
Accepted Manuscript
Journal Name:
Protein Science
Additional Journal Information:
Journal Volume: 24; Journal Issue: 1; Journal ID: ISSN 0961-8368
Publisher:
The Protein Society
Research Org:
Oregon State Univ., Corvallis, OR (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES thiol oxidation; 3-mercaptopropionate dioxygenase; sulfur metabolism; structural genomics; metalloenzyme; non-heme iron