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Mechanisms of Acinetobacter baumannii Capsular Polysaccharide Cleavage by Phage Depolymerases

Y A Knirel1, M M Shneider2,3, A V Popova3,4,5

  • 1Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 119991, Russia. yknirel@gmail.com.

Biochemistry. Biokhimiia
|June 24, 2020
PubMed

Insights

Bacteriophage tailspikes, enzymes that degrade bacterial capsules, were studied. These depolymerases show specific mechanisms for cleaving Acinetobacter baumannii capsular polysaccharides, offering potential antimicrobial strategies.

Area of Science:

  • Microbiology
  • Virology
  • Biochemistry

Background:

  • Acinetobacter baumannii is a major cause of hospital-acquired infections worldwide.
  • Its capsular polysaccharide (CPS) layer protects against environmental threats and host defenses.
  • Bacteriophages utilize tailspikes, a type of depolymerase, to degrade bacterial CPS.

Purpose of the Study:

  • To investigate the interaction between bacteriophage tailspikes and Acinetobacter baumannii CPS.
  • To characterize the enzymatic mechanisms employed by these tailspikes.

Main Methods:

  • Studied four lytic phages carrying depolymerases targeting A. baumannii.
  • Identified and characterized the specific CPS cleavage activities of the tailspikes.

Main Results:

  • Depolymerases from phages Fri1, AS12, and BS46 function as glycosidases, hydrolyzing CPS from specific A. baumannii strains.
  • gp54 depolymerase from phage AP22 acts as a polysaccharide lyase, cleaving CPS via β-elimination at hexuronic acid residues.

Conclusions:

  • Bacteriophage depolymerases exhibit diverse mechanisms for degrading A. baumannii CPS.
  • Understanding these interactions is crucial for developing phage-based therapies against A. baumannii infections.

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