following-real-time-impact-pneumococcal-virulence-factors-an-acute

Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria

Pneumonia is one of the major health care problems in developing and industrialized countries and is associated with considerable morbidity and mortality. ...

University of Greifswald

The respiratory pathogen Streptococcus pneumoniae has evolved efficient mechanisms to resist oxidative stress conditions and to displace other bacteria in the nasopharynx. Here we characterize at physiological, functional and structural levels two novel surface-exposed thioredoxin-family lipoproteins, Etrx1 and Etrx2. The impact of both Etrx proteins and their redox partner methionine sulfoxide reductase SpMsrAB2 on pneumococcal pathogenesis was assessed in mouse virulence studies and phagocytosis assays. The results demonstrate that loss of function of either both Etrx proteins or SpMsrAB2 dramatically attenuated pneumococcal virulence in the acute mouse pneumonia model and that Etrx proteins compensate each other. The deficiency of Etrx proteins or SpMsrAB2 further enhanced bacterial uptake by macrophages, and accelerated pneumococcal killing by H2 O2 or free methionine sulfoxides (MetSO). Moreover, the absence of both Etrx redox pathways provokes an accumulation of oxidized SpMsrAB2 in vivo. Taken together our results reveal insights into the role of two extracellular electron pathways required for reduction of SpMsrAB2 and surface-exposed MetSO. Identification of this system and its target proteins paves the way for the design of novel antimicrobials.

Molecular architecture of Streptococcus pneumoniae surface thioredoxin-fold lipoproteins crucial for extracellular oxidative stress resistance and maintenance of virulence.

Surface proteins are important for the fitness and virulence of the Gram-positive pathogen Streptococcus pneumoniae. They are crucial for interaction of the pathogen with its human host during infection. Therefore, the analysis of the pneumococcal surface proteome is an important task that requires powerful tools. In this study, two different methods, an optimized biotinylation approach and shaving with trypsin beads, were applied to study the pneumococcal surface proteome and to identify surface-exposed protein domains, respectively. The identification of nearly 95% of the predicted lipoproteins and 75% of the predicted sortase substrates reflects the high coverage of the two classical surface protein classes accomplished in this study. Furthermore, the biotinylation approach was applied to study the impact of an impaired lipoprotein maturation pathway on the cell envelope proteome and exoproteome. Loss of the lipoprotein diacylglyceryl transferase Lgt leads to striking changes in the lipoprotein distribution. Many lipoproteins disappear from the surface proteome and accumulate in the exoproteome. Further insights into lipoprotein processing in pneumococci are provided by immunoblot analyses of bacterial lysates and corresponding supernatant fractions. Taken together, the first comprehensive overview of the pneumococcal surface and exoproteome is presented, and a model for lipoprotein processing in S. pneumoniae is proposed.

Mohammed R. Abdullah

Department Genetics of Microorganisms,
Interfaculty Institute for Genetics and Functional Genomics,
Department Genetics of Microorganisms, Interfaculty Institute for Genetics and Functional Genomics

University of Greifswald

Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria

Mohammed R. Abdullah

Department Genetics of Microorganisms,Interfaculty Institute for Genetics and Functional Genomics,Department Genetics of Microorganisms, Interfaculty Institute for Genetics and Functional Genomics

University of Greifswald

Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria

Department Genetics of Microorganisms,
Interfaculty Institute for Genetics and Functional Genomics,
Department Genetics of Microorganisms, Interfaculty Institute for Genetics and Functional Genomics