Poster Presentation 2014 International Biophysics Congress

In silico studies of enzimes from indole-3-acetic acid metabolic pathways in the endophytic bacterium gluconacetobacter diazotrophicus (#373)

Daniel M.C. Leite 1 , Leticia M.S. Lery 1 , Paulo Mascarello Bisch 1
  1. Institut of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil

Gluconacetobacter diazotrophicus is an endophytic nitrogen-fixing Gram-negative bacterium. Originally isolated from sugarcane, it propitiates several benefits to the host, as the ability of producing plant growth-promoting hormones, especially indole-3-acetic acid (IAA).

The present work aimed to identify and characterize metabolic pathways and enzymes involved in the production of IAA in G. diazotrophicus. Bioinformatics tools were used to construct protein sequence profiles (PSPs) of proteins known to be involved in IAA biosynthesis. These profiles were used to search for similar sequences in G. diazotrophicus. 3D models were built for some of the identified enzymes through comparative modeling.

We identified seven enzymes potentially associated with three tryptophan-related pathways in G. diazotrophicus. We have successfully built 3D models of good quality for five G. diazotrophicus proteins potentially related to IAA biosynthesis.

The use of PSPs followed by comparative modeling provides a very efficacious annotation approach, allowing a reliable identification and characterization of potential IAA-related pathways in G. diazotrophicus. For instance, it is the first time that structural features for IAA-related proteins were elucidated in G. diazotrophicus. Among several aspects, one being able to propose a new substrate selection mechanism for arylacetonitrilases, a major enzyme from the indole-3-acetonitrile pathway, an aspect never described before.