NMR assignment of actin depolymerizing and dynamics regulatory protein from Leishmania donovani

Leishmania donovani cofilin displays low sequence similarity to other mammalian cofilins and also possesses characteristic activity of its own. Determination of its solution structure would facilitate understanding of the molecular mechanism of actin dynamics regulation in this disease causing pathogen

Solution structure and dynamics of ADF/cofilin from Leishmania donovani

Leishmania donovani ADF/cofilin (LdCof) is a novel member of ADF/cofilin family. LdCof depolymerizes, but does not co-sediment with, rabbit muscle actin filaments. Its F-actin depolymerizing activity is pH independent. Further, it possesses weak F-actin severing activity. In order to better understand its characteristic properties, we have determined the solution NMR structure of LdCof and have analyzed protein backbone dynamics from 15N-relaxation measurements. The structure of LdCof possesses a conserved ADF/cofilin fold with a central mixed β -sheet consisting of six β -strands which is surrounded by five α -helices. LdCof structure has conserved G/F-actin binding site which includes the characteristic long kinked α -helix (α 3). LdCof binds to rabbit muscle ADP-G-actin with 1:1 stoichiometry (Kd ~ 0.2 μ M). The F-actin binding site is not well formed and analysis of 15N-relaxation data shows that residues in the β 4-β 5 loop region and C-terminal are relatively flexible, which seems to be a determinant for the low F-actin severing activity of LdCof