Staphylococcus aureus β-Toxin Mutants Are Defective in Biofilm Ligase and Sphingomyelinase Activity, and Causation of Infective Endocarditis and Sepsis

Alfa Herrera; Bao G Vu; Christopher S Stach; Joseph A Merriman; Alexander R Horswill; Wilmara Salgado-Pabón; Patrick M Schlievert

doi:10.1021/acs.biochem.6b00083

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Staphylococcus aureus β-Toxin Mutants Are Defective in Biofilm Ligase and Sphingomyelinase Activity, and Causation of Infective Endocarditis and Sepsis

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Staphylococcus aureus β-Toxin Mutants Are Defective in Biofilm Ligase and Sphingomyelinase Activity, and Causation of Infective Endocarditis and Sepsis

Alfa Herrera, Bao G Vu, Christopher S Stach, Joseph A Merriman, Alexander R Horswill, Wilmara Salgado-Pabón and Patrick M Schlievert

Biochemistry (Easton), Vol.55(17), pp.2510-2517

05/03/2016

DOI: 10.1021/acs.biochem.6b00083

PMCID: PMC5312681

PMID: 27015018

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Abstract

β-Toxin is an important virulence factor of Staphylococcus aureus, contributing to colonization and development of disease [Salgado-Pabon, W., et al. (2014) J. Infect. Dis. 210, 784-792; Huseby, M. J., et al. (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 14407-14412; Katayama, Y., et al. (2013) J. Bacteriol. 195, 1194-1203]. This cytotoxin has two distinct mechanisms of action: sphingomyelinase activity and DNA biofilm ligase activity. However, the distinct mechanism that is most important for its role in infective endocarditis is unknown. We characterized the active site of β-toxin DNA biofilm ligase activity by examining deficiencies in site-directed mutants through in vitro DNA precipitation and biofilm formation assays. Possible conformational changes in mutant structure compared to that of wild-type toxin were assessed preliminarily by trypsin digestion analysis, retention of sphingomyelinase activity, and predicted structures based on the native toxin structure. We addressed the contribution of each mechanism of action to producing infective endocarditis and sepsis in vivo in a rabbit model. The H289N β-toxin mutant, lacking sphingomyelinase activity, exhibited lower sepsis lethality and infective endocarditis vegetation formation compared to those of the wild-type toxin. β-Toxin mutants with disrupted biofilm ligase activity did not exhibit decreased sepsis lethality but were deficient in infective endocarditis vegetation formation compared to the wild-type protein. Our study begins to characterize the DNA biofilm ligase active site of β-toxin and suggests β-toxin functions importantly in infective endocarditis through both of its mechanisms of action.

Sphingomyelin Phosphodiesterase - genetics

Endocarditis - pathology

Sepsis - etiology

Staphylococcus aureus - enzymology

Hemolysin Proteins - genetics

Biofilms - growth & development

Male

Hemolysin Proteins - chemistry

Staphylococcal Infections - complications

Endocarditis - enzymology

Sepsis - pathology

Ligases - deficiency

Sphingomyelin Phosphodiesterase - metabolism

Bacterial Toxins - genetics

Female

Staphylococcal Infections - microbiology

Biofilms - drug effects

Staphylococcus aureus - genetics

Amino Acid Sequence

Endocarditis - etiology

Rabbits

Sphingomyelin Phosphodiesterase - chemistry

Hemolysin Proteins - adverse effects

Bacterial Toxins - adverse effects

Bacterial Toxins - chemistry

Sphingomyelin Phosphodiesterase - deficiency

Bacterial Toxins - metabolism

Animals

Sepsis - enzymology

Protein Conformation

Hemolysin Proteins - metabolism

Sphingomyelin Phosphodiesterase - adverse effects

Details

Title: Subtitle: Staphylococcus aureus β-Toxin Mutants Are Defective in Biofilm Ligase and Sphingomyelinase Activity, and Causation of Infective Endocarditis and Sepsis
Creators: Alfa Herrera - Department of Microbiology, University of Iowa Carver College of Medicine , Iowa City, Iowa 52242, United States
Bao G Vu - Department of Microbiology, University of Iowa Carver College of Medicine , Iowa City, Iowa 52242, United States
Christopher S Stach - Department of Microbiology, University of Iowa Carver College of Medicine , Iowa City, Iowa 52242, United States
Joseph A Merriman - Department of Microbiology, University of Iowa Carver College of Medicine , Iowa City, Iowa 52242, United States
Alexander R Horswill - Department of Microbiology, University of Iowa Carver College of Medicine , Iowa City, Iowa 52242, United States
Wilmara Salgado-Pabón - Department of Microbiology, University of Iowa Carver College of Medicine , Iowa City, Iowa 52242, United States
Patrick M Schlievert - Department of Microbiology, University of Iowa Carver College of Medicine , Iowa City, Iowa 52242, United States
Resource Type: Journal article
Publication Details: Biochemistry (Easton), Vol.55(17), pp.2510-2517
DOI: 10.1021/acs.biochem.6b00083
PMID: 27015018
PMCID: PMC5312681
NLM abbreviation: Biochemistry
ISSN: 0006-2960
eISSN: 1520-4995
Publisher: United States
Grant note: P30 DK054759 / NIDDK NIH HHS
Language: English
Date published: 05/03/2016
Academic Unit: Molecular Physiology and Biophysics; Microbiology and Immunology; Internal Medicine
Record Identifier: 9984001131802771

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