Characterization of unusual families of ATG8-like proteins and ATG12 in the protozoan parasite Leishmania major

Autophagy. 2009 Feb;5(2):159-72. doi: 10.4161/auto.5.2.7328. Epub 2009 Feb 4.


Leishmania major possesses, apparently uniquely, four families of ATG8-like genes, designated ATG8, ATG8A, ATG8B and ATG8C, and 25 genes in total. L. major ATG8 and examples from the ATG8A, ATG8B and ATG8C families are able to complement a Saccharomyces cerevisiae ATG8-deficient strain, indicating functional conservation. Whereas ATG8 has been shown to form putative autophagosomes during differentiation and starvation of L. major, ATG8A primarily form puncta in response to starvation-suggesting a role for ATG8A in starvation-induced autophagy. Recombinant ATG8A was processed at the scissile glycine by recombinant ATG4.2 but not ATG4.1 cysteine peptidases of L. major and, consistent with this, ATG4.2-deficient L. major mutants were unable to process ATG8A and were less able to withstand starvation than wild-type cells. GFP-ATG8-containing puncta were less abundant in ATG4.2 overexpression lines, in which unlipidated ATG8 predominated, which is consistent with ATG4.2 being an ATG8-deconjugating enzyme as well as an ATG8A-processing enzyme. In contrast, recombinant ATG8, ATG8B and ATG8C were all processed by ATG4.1, but not by ATG4.2. ATG8B and ATG8C both have a distinct subcellular location close to the flagellar pocket, but the occurrence of the GFP-labeled puncta suggest that they do not have a role in autophagy. L. major genes encoding possible ATG5, ATG10 and ATG12 homologues were found to complement their respective S. cerevisiae mutants, and ATG12 localized in part to ATG8-containing puncta, suggestive of a functional ATG5-ATG12 conjugation pathway in the parasite. L. major ATG12 is unusual as it requires C-terminal processing by an as yet unidentified peptidase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Autophagy / drug effects
  • Cysteine Endopeptidases / metabolism
  • Cytoplasmic Structures / drug effects
  • Cytoplasmic Structures / metabolism
  • Fluorescence Resonance Energy Transfer
  • Genes, Protozoan
  • Genetic Complementation Test
  • Glycine / metabolism
  • Hydrolysis / drug effects
  • Kinetics
  • Leishmania major / cytology
  • Leishmania major / drug effects
  • Leishmania major / genetics
  • Leishmania major / metabolism*
  • Lipid Metabolism / drug effects
  • Molecular Sequence Data
  • Molecular Weight
  • Oligopeptides / metabolism
  • Parasites / cytology
  • Parasites / drug effects
  • Parasites / genetics
  • Parasites / metabolism*
  • Protease Inhibitors / pharmacology
  • Protozoan Proteins / chemistry
  • Protozoan Proteins / metabolism*
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / metabolism
  • Sequence Homology, Amino Acid
  • Substrate Specificity / drug effects


  • Oligopeptides
  • Protease Inhibitors
  • Protozoan Proteins
  • Recombinant Fusion Proteins
  • Cysteine Endopeptidases
  • Glycine