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Crystal and solution structures of a prokaryotic M16B peptidase: an open and shut case

Alexander E Aleshin1, Svetlana Gramatikova, Gregory L Hura

  • 1Burnham Institute for Medical Research, La Jolla, CA 92037, USA.

Structure (London, England : 1993)
|November 17, 2009
PubMed

Insights

This study reveals a prokaryotic M16B peptidase with dual characteristics, exhibiting features of both processing proteases and peptidasomes. Clam-shell closure upon substrate binding is crucial for its proteolytic activity.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Enzymology

Background:

  • The M16 family of zinc peptidases contains homologous domains forming a clam-shell active site.
  • M16A/M16C subfamilies (peptidasomes) degrade peptides and adopt open/closed conformations.
  • Eukaryotic M16B subfamilies (processing proteases) have a partly-open conformation for signal sequence cleavage.

Purpose of the Study:

  • To determine the structures of a prokaryotic M16B peptidase.
  • To investigate its functional and structural characteristics.
  • To understand the evolutionary relationships within the M16 peptidase family.

Main Methods:

  • Solution and crystal structure determination of a prokaryotic M16B peptidase.
  • Biochemical assays to assess proteolytic activity and substrate binding.
  • Comparative analysis with known M16A/M16C and eukaryotic M16B peptidases.

Main Results:

  • The prokaryotic M16B peptidase forms stable open homodimers in solution.
  • It exhibits substrate-induced clam-shell closure, a feature of M16A/M16C peptidasomes.
  • Clam-shell closure is essential for proteolytic activity.

Conclusions:

  • Prokaryotic M16B peptidases may function as dimeric peptidasomes.
  • This finding suggests a potential evolutionary link between processing proteases and peptidasomes.
  • A model for M16 family evolution is proposed based on these findings.

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