Crystal structure of Leishmania major ADP-ribosylation factor-like 1 and a classification of related GTPase family members in this Kinetoplastid.

ADP-ribosylation factor-like (ARL) proteins are small GTPases that undergo conformational changes upon nucleotide binding, and which regulate the affinity of ARLs for binding other proteins, lipids or membranes. There is a paucity of structural data on this family of proteins in the Kinetoplastida, despite studies implicating them in key events related to vesicular transport and regulation of microtubule-dependent processes. The crystal structure of Leishmania major ARL1 in complex with GDP has been determined to 2.1 Å resolution and reveals a high degree of structural conservation with human ADP-ribosylation factor 1 (ARF1). Putative L. major and Trypanosoma brucei ARF/ARL family members have been classified based on structural considerations, amino acid sequence conservation combined with functional data on Kinetoplastid and human orthologues. This classification may guide future studies designed to elucidate the function of specific family members.