Cloning and structure-function analysis of the Leishmania donovani kinetoplastid membrane protein-11.
This report describes the complete translated gene sequence, predicted secondary structure and lipid bilayer association of a novel kinetoplastid membrane protein (KMP-11) from Leishmania donovani promastigotes. KMP-11 was previously referred to as the lipophosphoglycan-associated protein (LPGAP). The isolation, species distribution and chemical characterization, including a partial protein sequence analysis and post-translational modifications, of this major membrane component have been described [Jardim, Funk, Caprioli and Olafson (1995) Biochem. J. 305, 307-313]. C.d. measurements of KMP-11 indicated a very high helical content estimated to be approximately 86% in trifluoroethanol. This was in agreement with computer-based secondary-structure analyses which predicted KMP-11 to be almost exclusively alpha-helical, with the protein adopting a helix-loop-helix motif. Arrangement of the residues located in the putative helical regions on an Edmundson helical wheel showed that this molecule could have a strongly amphipathic conformation and provided an explanation for how such a highly charged protein might be inserted into the plasma membrane. Evidence in support of KMP-11 association with lipid bilayers was provided by showing that KMP-11 could mediate carboxyfluorescein release from liposomes. These findings suggested that KMP-11 may function in part to increase bilayer pressure, stabilizing molecules such as lipophosphoglycan within the parasite pellicular membrane.
Jardim
A
A
Department of Biochemistry and Microbiology, University of Victoria, B.C. Canada.
Hanson
S
S
Ullman
B
B
McCubbin
W D
WD
Kay
C M
CM
Olafson
R W
RW
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D003001:Cloning, Molecular; D003198:Computer Simulation; D006801:Humans; D007893:Leishmania donovani / Q000737:chemistry / Q000502:physiology*; D008081:Liposomes / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
D008081:Liposomes; D008562:Membrane Glycoproteins; D015800:Protozoan Proteins; C090009:kinetoplastid membrane protein 11, Leishmania donovani