Scholarlink

<p>Bacterial secretion of extracellular polysaccharides is essential for surface colonization, biofilm formation, and pathogenesis. In diderm bacteria, such polymers traverse the periplasm and outer membrane (OM) through outer-membrane polysaccharide export (OPX) proteins that form secretion pores. Among them, Class-3 OPX proteins are the most widespread but lack an OM-spanning pore domain, leaving their mechanisms poorly understood. Here, we characterize WzaB from <i>Myxococcus xanthus</i> as a model for Class-3 OPX-mediated secretion. Structural and molecular dynamics analyses reveal that WzaB exists as a rigid monomer in solution, in contrast to the constitutive octamerization observed in Class-1 OPX proteins. Biochemical, biophysical, and in vivo analyses show that WzaB oligomerizes in a lipidation-dependent manner and directly interacts with the OM porin WzpB and the inner-membrane co-polymerase WzcB, with binding determinants mapped for both partners. Together, these proteins assemble into a trans-envelope polysaccharide secretion complex, redefining OPX function and revealing a distinct translocon architecture for Class-3 OPX systems.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Mechanism of trans-envelope bacterial polysaccharide secretion in Class-3 outer-membrane polysaccharide export (OPX) protein systems

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年1月16日

查看全文
  • Abdelkader Mellouk,
  • Kenny Ngo,
  • Ahmad A. Kezzo,
  • Cyrielle Martini,
  • Tanos C. C. França,
  • Steven R. Laplante,
  • Salim T. Islam,
  • Charles Calmettes

摘要

Bacterial secretion of extracellular polysaccharides is essential for surface colonization, biofilm formation, and pathogenesis. In diderm bacteria, such polymers traverse the periplasm and outer membrane (OM) through outer-membrane polysaccharide export (OPX) proteins that form secretion pores. Among them, Class-3 OPX proteins are the most widespread but lack an OM-spanning pore domain, leaving their mechanisms poorly understood. Here, we characterize WzaB from Myxococcus xanthus as a model for Class-3 OPX-mediated secretion. Structural and molecular dynamics analyses reveal that WzaB exists as a rigid monomer in solution, in contrast to the constitutive octamerization observed in Class-1 OPX proteins. Biochemical, biophysical, and in vivo analyses show that WzaB oligomerizes in a lipidation-dependent manner and directly interacts with the OM porin WzpB and the inner-membrane co-polymerase WzcB, with binding determinants mapped for both partners. Together, these proteins assemble into a trans-envelope polysaccharide secretion complex, redefining OPX function and revealing a distinct translocon architecture for Class-3 OPX systems.