HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 283, Issue 16, 10377-10384, April 18, 2008

This Article Full Text Full Text (PDF) All Versions of this Article: 283/16/10377    most recent M709285200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Dou, Z. Articles by Cannon, G. C. Search for Related Content PubMed PubMed Citation Articles by Dou, Z. Articles by Cannon, G. C. Social Bookmarking                      What's this?

CO₂ Fixation Kinetics of Halothiobacillus neapolitanus Mutant Carboxysomes Lacking Carbonic Anhydrase Suggest the Shell Acts as a Diffusional Barrier for CO₂^*

Zhicheng Dou, Sabine Heinhorst, Eric B. Williams, C. Daniel Murin, Jessup M. Shively, and Gordon C. Cannon¹

From the Department of Chemistry and Biochemistry, The University of Southern Mississippi, Hattiesburg, Mississippi 39406-0001 and the Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina 29634-1903

The widely accepted models for the role of carboxysomes in the carbon-concentrating mechanism of autotrophic bacteria predict the carboxysomal carbonic anhydrase to be a crucial component. The enzyme is thought to dehydrate abundant cytosolic bicarbonate and provide ribulose 1.5-bisphosphate carboxylase/oxygenase (RubisCO) sequestered within the carboxysome with sufficiently high concentrations of its substrate, CO₂, to permit its efficient fixation onto ribulose 1,5-bisphosphate. In this study, structure and function of carboxysomes purified from wild type Halothiobacillus neapolitanus and from a high CO₂-requiring mutant that is devoid of carboxysomal carbonic anhydrase were compared. The kinetic constants for the carbon fixation reaction confirmed the importance of a functional carboxysomal carbonic anhydrase for efficient catalysis by RubisCO. Furthermore, comparisons of the reaction in intact and broken microcompartments and by purified carboxysomal RubisCO implicated the protein shell of the microcompartment as impeding diffusion of CO₂ into and out of the carboxysome interior.

Received for publication, November 12, 2007 , and in revised form, January 24, 2008.

^* This work was supported by Grants MCB-0444568 and DMR-0213883 from the National Science Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: Dept. of Chemistry and Biochemistry, The University of Southern Mississippi, 118 College Dr. #5043, Hattiesburg, MS 39406-0001. Tel.: 601-266-4221; Fax: 601-266-6075; E-mail: gordon.cannon{at}usm.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				M. Sagermann, A. Ohtaki, and K. Nikolakakis Crystal structure of the EutL shell protein of the ethanolamine ammonia lyase microcompartment PNAS, June 2, 2009; 106(22): 8883 - 8887. [Abstract] [Full Text] [PDF]