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Journal of Bacteriology, February 2008, p. 1459-1472, Vol. 190, No. 4
0021-9193/08/$08.00+0     doi:10.1128/JB.01688-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Moraxella catarrhalis Synthesizes an Autotransporter That Is an Acid Phosphatase{triangledown}

Todd C. Hoopman,1,2 Wei Wang,1 Chad A. Brautigam,3 Jennifer L. Sedillo,1 Thomas J. Reilly,4 and Eric J. Hansen1*

Department of Microbiology,1 Department of Internal Medicine, Pulmonary and Critical Care Medicine,2 Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390,3 Department of Veterinary Pathobiology and Veterinary, Medical Diagnostic Laboratory, University of Missouri, Columbia, Missouri 652114

Received 19 October 2007/ Accepted 21 November 2007

Moraxella catarrhalis O35E was shown to synthesize a 105-kDa protein that has similarity to both acid phosphatases and autotransporters. The N-terminal portion of the M. catarrhalis acid phosphatase A (MapA) was most similar (the BLAST probability score was 10–10) to bacterial class A nonspecific 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 Escherichia coli confirmed the presence of acid phosphatase activity in the MapA protein. The MapA protein was shown to be localized to the outer membrane of M. catarrhalis and was not detected either in the soluble cytoplasmic fraction from disrupted M. catarrhalis cells or in the 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 the 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 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.

* Corresponding author. Mailing address: Department of Microbiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9048. Phone: (214) 648-5974. Fax: (214) 648-5905. E-mail: eric.hansen{at}utsouthwestern.edu

{triangledown} Published ahead of print on 7 December 2007.

Journal of Bacteriology, February 2008, p. 1459-1472, Vol. 190, No. 4
0021-9193/08/$08.00+0     doi:10.1128/JB.01688-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Reilly, T. J., Chance, D. L., Calcutt, M. J., Tanner, J. J., Felts, R. L., Waller, S. C., Henzl, M. T., Mawhinney, T. P., Ganjam, I. K., Fales, W. H. (2009). Characterization of a Unique Class C Acid Phosphatase from Clostridium perfringens. Appl. Environ. Microbiol. 75: 3745-3754 [Abstract] [Full Text]  


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