Agamemnon James (A.J.) Carpousis is a Research Director in the CNRS. He graduated with honors in Biochemistry from the University of Pennsylvania and then did his doctoral studies in the Molecular Biology program at UCLA. His PhD work was on the mechanism of transcription initiation by Escherichia coli RNA polymerase. After postdoctoral research at UC Santa Barbara and the University of Geneva, A.J. Carpousis joined the LMGM, which is a CNRS Microbial Molecular Genetics Laboratory at the University of Toulouse. His research in Geneva contributed to the discovery that RNase E, which is an essential ribonuclease in E. coli, is a key enzyme in the initiation of mRNA degradation. In subsequent research, he purified RNase E and showed that it associates with other proteins involved in mRNA degradation forming a multienzyme complex, which is now known as the RNA degradosome. His group in Toulouse showed that RNase E has a composite structure consisting of a catalytic domain and a large non-catalytic region that serves as the scaffold for interactions with other components of the RNA degradosome. Other work includes studies on the role of RhlB, PNPase and poly(A) polymerase in mRNA degradation, and identification and characterization of beta-CASP ribonucleases in the Archaea. More recently, A.J. Carpousis and his colleagues showed that the RNA degradosome is localized to the inner cytoplasmic membrane of E. coli. They characterized a conserved element in the non-catalytic region of RNase E that directly anchors the RNA degradosome to the phospholipid bilayer of the inner membrane. RNA degradosomes on the inner membrane are highly dynamic forming short-lived clusters that are hypothesized to be centers of mRNA degradation. His group currently uses molecular genetics, biochemistry, high-density sequencing methods and super-resolution microscopy to address the question of the composition and supramolecular structure of the RNA degradosome clusters.