The branched-chain amino acid transporter AAT10.2 of Trypanosoma brucei is regulated by substrate availability

ABSTRACT: A phosphoproteome analysis of procyclic form T. brucei revealed many amino acid transporters (AATs) of the amino acid/auxin permease (AAAP) family with phosphorylated residues exclusively in their hydrophilic N-terminal domain. AAT10.2, which contained multiple phosphorylated residues, was further characterized and shown to be localized at the plasma membrane and the flagellar pocket. RNAi in procyclic form T. brucei revealed that AAT10.2 is essential and the main transporter for branched-chain amino acids (BCAA). Furthermore, the abundance of AAT10.2 protein is regulated by BCAA levels. However, mutation of the identified phosphorylation-sites or truncation of the first 35 amino acids did not affect affinity, localization, or the BCAA-dependent regulation of AAT10.2. The non-phosphorylatable 3xTy-STA-AAT10.2* variant, in which N-terminal serine and threonine residues were mutated to alanine, showed increased protein levels compared to native Ty-tagged AAT10.2* or the phosphomimicking variant (3xTy-STD-AAT10.2*) with aspartate replacing serine and threonine in the N-terminal region. Truncation of the N-terminal domain reduced the overall AAT10.2 abundance and internal BCAA levels in short-term experiments, and decreased T. brucei growth when BCAA availability was limited. These findings establish AAT10.2 as essential, substrate-regulated BCAA transporter in procyclic form T. brucei.

INSTRUMENT(S):

ORGANISM(S): Trypanosoma Brucei

SUBMITTER: Manfred Heller  

LAB HEAD: Doris Rentsch

PROVIDER: PXD079824 | Pride | 2026-09-14

REPOSITORIES: Pride