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The putative penicillin-binding proteins 1 and 2 are important for viability, growth and cell morphology of Brucella

Aloka B Bandara1, Gerhardt G Schurig, Nammalwar Sriranganathan

  • 1Department of Biomedical Sciences & Pathobiology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0910, USA. abandara@vt.edu

Veterinary Microbiology
|September 24, 2008
PubMed

Insights

Penicillin-binding proteins (PBPs) are crucial for bacterial cell walls. Disrupting Brucella melitensis pbp-1C affects growth and morphology but not infectivity, while other PBPs are essential for survival.

Area of Science:

  • Microbiology
  • Bacterial Cell Wall Synthesis
  • Bacterial Pathogenesis

Background:

  • Penicillin-binding proteins (PBPs) are essential enzymes for bacterial cell wall peptidoglycan synthesis.
  • Brucella melitensis, an intracellular pathogen, possesses seven pbp genes.
  • Understanding PBP functions is critical for developing novel antimicrobial strategies.

Purpose of the Study:

  • To investigate the roles of pbp-1 and pbp-2 genes in Brucella melitensis viability, cell morphology, and infectivity.
  • To determine the essentiality of specific PBP genes for B. melitensis survival and pathogenesis.

Main Methods:

  • Generation of a recombinant B. melitensis strain (16MDeltapbp1C) by disrupting the pbp-1C gene using allelic exchange.
  • Comparative analysis of colony morphology, growth rates in vitro, and cell shape using electron microscopy.
  • Assessment of intracellular persistence in a mouse macrophage cell line (J774.1) and in vivo infectivity in BALB/c mice.

Main Results:

  • The 16MDeltapbp1C strain exhibited slower growth and smaller colony formation compared to wild-type B. melitensis.
  • Electron microscopy revealed a morphological shift from cocco-bacillus to spherical in the 16MDeltapbp1C strain.
  • pbp-1C disruption did not impair intracellular persistence or infectivity in mouse models.
  • Attempts to disrupt pbp-1A, pbp-1B, and pbp-2 genes were unsuccessful, indicating their essentiality for B. melitensis viability.

Conclusions:

  • pbp-1C plays a significant role in regulating in vitro growth rate and cell morphology of B. melitensis.
  • pbp-1A, pbp-1B, and pbp-2 are indispensable for the viability of B. melitensis.
  • Targeting non-essential PBPs like pbp-1C may offer novel therapeutic avenues with potentially reduced impact on essential bacterial functions.

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