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Contact-dependent growth inhibition systems in Acinetobacter

Eliana De Gregorio1,2, Raffaele Zarrilli3, Pier Paolo Di Nocera4

  • 1Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Via Sergio Pansini 5, Naples, 80131, Italy.

Scientific Reports
|January 19, 2019
PubMed

Insights

Researchers identified over 40 bacterial contact-dependent growth inhibition (CDI) systems in Acinetobacter. These systems were classified into two types, Type-I and Type-II, based on protein size and structural features.

Area of Science:

  • Microbiology
  • Bacterial Genetics
  • Protein Structure

Background:

  • Bacterial contact-dependent growth inhibition (CDI) systems mediate inter-bacterial interactions.
  • CDI systems involve CdiA proteins exported by CdiB proteins, delivering toxins to target cells.
  • Self bacteria possess CdiI antitoxins, while non-self bacteria are susceptible to CdiA-mediated growth inhibition.

Purpose of the Study:

  • To identify and classify different CDI systems within pathogenic Acinetobacter genomes.
  • To characterize the structural and genetic distinctions between identified CDI system types.

Main Methods:

  • In silico genomic surveys of pathogenic Acinetobacter species.
  • Comparative analysis of CdiA protein sequences, sizes, and domain structures.
  • Investigation of gene organization and potential sequence exchange mechanisms.

Main Results:

  • Over 40 distinct CDI systems were identified and categorized into Type-I and Type-II.
  • Type-II CdiA proteins are large with repeat arrays, while Type-I CdiAs are smaller with variable HET regions.
  • Significant differences were observed in CdiA-CT and pretoxin modules, as well as gene organization between Type-I and Type-II systems.

Conclusions:

  • Two distinct types of CDI systems, Type-I and Type-II, are prevalent in pathogenic Acinetobacter.
  • Structural and genetic variations suggest different evolutionary trajectories and functional adaptations of these CDI systems.
  • The distribution of Type-I and Type-II systems varies across Acinetobacter species, indicating potential species-specific roles.

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