Cellular organelles facilitate dimerization of a newly identified Arf from Chlamydomonas reinhardtii. Issue 6 (10th November 2014)

• Record Type: Journal Article
• Authors: Ranjan, Peeyush; Kashyap, Rudra Shankar; Goel, Manisha; Veetil, Sindhu Kandoth; Kateriya, Suneel; Cock, M.
• Is Part Of: Journal of phycology. Volume 50:Issue 6(2014:Dec.)
• Page Start: 1137
• Page End: 1145
• Publication Date: 2014-11-10
• Subjects: Algae -- Periodicals; 579.8
• DOI: 10.1111/jpy.12245
• Languages: English
• ISSNs: 0022-3646

Abstract

<abstract abstract-type="main" id="jpy12245-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>GTPases of the Ras superfamily regulate a wide variety of cellular processes including vesicular transport and various secretory pathways of the cell. ADP – ribosylation factor (ARF) belongs to one of the five major families of the Ras superfamily and serves as an important component of vesicle formation and transport machinery of the cells. The binding of GTP to these Arfs and its subsequent hydrolysis, induces conformational changes in these proteins leading to their enzymatic activities. The dimeric form of Arf is associated with membrane pinch‐off during vesicle formation. In this report, we have identified an arf gene from the unicellular green alga <italic>Chlamydomonas reinhardtii</italic>, <italic> Cr</italic>Arf, and showed that the oligomeric state of the protein in <italic>C. renhardtii</italic> is modulated by the cellular membrane environment of the organism. Protein cross‐linking experiments showed that the purified recombinant <italic>Cr</italic>Arf has the ability to form a dimer. Both the 20‐kDa monomeric and 40‐kDa dimeric forms of <italic>Cr</italic>Arf were recognized from <italic>Chlamydomonas</italic> total cell lysate (<italic>Cr</italic>TLC) and purified recombinant <italic>Cr</italic>Arf by the <italic>Cr</italic>Arf specific antibody. The membranous environment of the cell appeared to facilitate dimerization of the <italic>Cr</italic>Arf, as dimeric form was found exclusively associated with the membrane bound organelles. The subcellular localization studies in <italic>Chlamydomonas</italic> suggested that <italic>Cr</italic>Arf mainly localized in the cytosol and was mislocalized in vesicle transport machinery inhibitor treated cells. This research sheds light on the importance of the cellular membrane environment for regulating the oligomeric state of <italic>Cr</italic>Arf protein in this organism and associated functional role.</p> </abstract>