Research Seminar - Hossein Amiri

During protein synthesis which occurs in all cells, the ribosome translocates along mRNA and reads it codon by codon.  Translocation is an elaborate dance: conformational changes occur in an orderly fashion between the large and small ribosomal subunits and between the head and body domains of the small subunit among others.  How these conformational changes, which are catalyzed by the elongation factor EF-G, drive mRNA translocation is not fully understood.  In particular, the choreography of the dance, the timing of various conformational changes with respect to EF-G binding and mRNA translocation, has so far been studied mainly in bulk experiments in which the order of events is inferred indirectly from the ensemble average.  We have employed single-molecule force spectroscopy with optical tweezers to isolate individual ribosomes and follow their translocation in real time with nanometer and millisecond resolution while simultaneously probing EF-G binding or ribosomal conformational changes using single-molecule fluorescence and Forster resonance energy transfer (FRET) measurements. This powerful combination yields a wealth of information on ribosomal dynamics and provides a rare direct glimpse at the intricate molecular mechanism of translocation .

Hossein Amiri is a postdoctoral researcher at the laboratory of Professor Carlos Bustamante at UC Berkeley, studying the molecular mechanism of ribosomal mRNA translocation using biochemical and biophysical approaches. He obtained his PhD in Molecular, Cell, and Developmental Biology in 2017 from UC Santa Cruz, where he worked in the laboratory of Professor Harry Noller to study the structural basis of ribosomal mRNA helicase activity.