title: Functional role of lysine 12 in Leishmania major AQP1.
abstract: Leishmania major aquaglyceroporin (AQP1) is an adventitious metalloid channel that allows the bidirectional movement of arsenite and antimonite. Here we demonstrate that AQP1 is subjected to proteasome-dependent degradation. Treatment of Leishmania promastigotes with the proteasome inhibitor MG132 resulted in increased AQP1 accumulation. Site-directed mutagenesis in AQP1 revealed that alteration of lysine 12 to either alanine or arginine improves protein stability. AQP1 expression is stabilized by mitogen-activated protein kinase 2 (MPK2). Cells expressing a dominant-negative MPK2 mutant exhibited severely reduced AQP1 expression, which could be reversed upon addition of MG132. Interestingly, the dominant-negative MPK2 mutant could not destabilize either AQP1K12A or AQP1K12R. While stabilization of AQP1 by MPK2 leads to its relocalization from flagellum to the entire surface of the parasite, altered AQP1K12A or AQP1K12R was restricted to flagellum only. Our data demonstrate that lysine 12 is targeted for proteasomal degradation of AQP1 and plays an integral role in subcellular localization of AQP1 as well as its interaction with MPK2. This work also raises the possibility that a strategy combining antimonial with a proteasome inhibitor may be an effective combination regimen against diverse forms of leishmaniasis.
authors.affiliation: Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida 33199, USA.
authors.forename: Mansi
authors.initials: M
authors.lastname: Sharma
authors.affiliation: Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida 33199, USA.
authors.forename: Goutam
authors.initials: G
authors.lastname: Mandal
authors.affiliation: Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida 33199, USA.
authors.forename: Srotoswati
authors.initials: S
authors.lastname: Mandal
authors.affiliation: Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida 33199, USA.
authors.forename: Hiranmoy
authors.initials: H
authors.lastname: Bhattacharjee
authors.affiliation: Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida 33199, USA. Electronic address: rmukhop@fiu.edu.
authors.forename: Rita
authors.initials: R
authors.lastname: Mukhopadhyay
mesh_terms: D019943:Amino Acid Substitution; D051397:Aquaglyceroporins / Q000235:genetics / Q000378:metabolism*; D004252:DNA Mutational Analysis; D018320:Leishmania major / Q000235:genetics / Q000502:physiology*; D007976:Leupeptins / Q000378:metabolism; D008239:Lysine / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D055550:Protein Stability; D021381:Protein Transport; D059748:Proteolysis
chemical_list: D051397:Aquaglyceroporins; D007976:Leupeptins; D020928:Mitogen-Activated Protein Kinases; D046988:Proteasome Endopeptidase Complex; D008239:Lysine; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde
keywords: Antimonite; Aquaglyceroporin; Leishmania; Post-translational regulation; Ubiquitination; Volume regulation