This Article Full Text (PDF) Other Versions of this Article: JB.01688-07v1 190/4/1459    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Hoopman, T. C. Articles by Hansen, E. J. Search for Related Content PubMed PubMed Citation Articles by Hoopman, T. C. Articles by Hansen, E. J.

 Previous Article  |  Next Article 

J. Bacteriol. doi:10.1128/JB.01688-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Moraxella catarrhalis Synthesizes An Autotransporter That Is An Acid Phosphatase

Department of Microbiology, Department of Internal Medicine, Pulmonary and Critical Care Medicine, and Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, and Department of Veterinary Pathobiology and Veterinary, Medical Diagnostic Laboratory, University of Missouri, Columbia, MO 65211

^* To whom correspondence should be addressed. Email: eric.hansen{at}utsouthwestern.edu.

	Abstract

Moraxella catarrhalis O35E was shown to synthesize a 105-kDa protein which has similarity to both acid phosphatases and autotransporters. The N-terminal portion of the M. catarrhalis acid phosphatase A (MapA) was most similar [BLAST probability score = 10^-10] to bacterial class A non-specific acid phosphatases. The central region of the MapA protein had similarity to passenger domains of other autotransporter proteins whereas the C-terminal portion of MapA resembled the translocation domain of conventional autotransporters. Cloning and expression of the M. catarrhalis mapA gene in E. coli confirmed the presence of acid phosphatase activity in this protein. The MapA protein was shown to be localized to the outer membrane of M. catarrhalis and was not detected in either the soluble cytoplasmic fraction from disrupted M. catarrhalis cells or in spent culture supernatant fluid from M. catarrhalis. Use of the predicted MapA translocation domain in a fusion construct with the passenger domain from another predicted M. catarrhalis autotransporter confirmed the translocation ability of this MapA domain. Inactivation of the mapA gene in M. catarrhalis strain O35E reduced acid phosphatase activity expressed by this organism and this mutation could be complemented in trans with the wild-type mapA gene. Nucleotide sequence analysis of the mapA gene from a total of six M. catarrhalis strains showed that this protein was highly conserved among strains of this pathogen. Site-directed mutagenesis of a critical histidine residue (H233A) in the predicted active site of the acid phosphatase domain in MapA eliminated acid phosphatase activity in the recombinant MapA protein. This is the first description of an autotransporter protein that expresses acid phosphatase activity.