Veerendra Kumara,b, Yun Chenb,1, Rya Erob,1, Tofayel Ahmedb,1, Jackie Tanb, Zhe Lia, Andrew See Weng Wongb, Shashi Bhushanb, and Yong-Gui Gaoa,b
a Institute of Molecular and Cell Biology, A*STAR, 138673, Singapore
b School of Biological Sciences, Nanyang Technological University, 637551, Singapore
1 equal contribution
Published in PNAS, 17th August 2015
BPI-inducible protein A (BipA) is a member of the family of ribosome-dependent translational GTPase (trGTPase) factors along with elongation factors G and 4 (EF-G and EF4). Despite being highly conserved in bacteria and playing a critical role in coordinating cellular responses to environmental changes, its structures (isolated and ribosome bound) remain elusive. Here, we present the crystal structures of apo form and GTP analog, GDP, and guanosine-3′,5′-bisdiphosphate (ppGpp)-bound BipA. In addition to having a distinctive domain arrangement, the C-terminal domain of BipA has a unique fold. Furthermore, we report the cryo-electron microscopy structure of BipA bound to the ribosome in its active GTP form and elucidate the unique structural attributes of BipA interactions with the ribosome and A-site tRNA in the light of its possible function in regulating translation.
Figure legend: Overall structure of BipA bound to ribosome.
(A) Overall view of the GTP form BipA–ribosome complex. BipA protein, 50S, and 30S subunits are shown as cryo-EM density in red, orange, and cyan, respectively. Structural landmarks of 50S are labeled for clarity.
(B) Structure of BipA with ribosome containing tRNAs. BipA (red), 30S subunit (cyan), A- (purple blue), P- (limon), and E- (violet) site tRNAs are shown as cryo-EM density. For clarity, the 50S subunit is not shown.