Understanding a key molecular recognition step in the assembly of the aminoglycoside antibiotic Butirosin

• Grant number: 25/09698-8
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: September 30, 2025
• End date: September 29, 2026
• Field of knowledge: Biological Sciences - Biophysics - Molecular Biophysics
• Principal Investigator: Marcio Vinicius Bertacine Dias
• Grantee: Renan Passos Freire
• Supervisor: Matthew Philip Crump
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: University of Bristol, England
• Associated to the scholarship: 22/13839-8 - Structural study of critical enzymes involved in the Butirosin biosynthesis, BP.DR

Abstract

The development of new molecules aiming at treating infections caused by resistant pathogens is a challenging path. Strategies to improve existing compounds or discover new ones require a lot of effort and, especially, time. There are difficulties in not only isolating a new compound but also finding interesting chemical modifications that could achieve efficiency in vivo. In this scenario, scientific communities around the world, with multidisciplinary approaches, put efforts to understand biosynthetic pathways, since most clinically relevant compounds are derived from natural sources. This project aims to understand molecular mechanisms involved in the incorporation of (S)-4-amino-2-hydroxybutyric acid (AHBA) moiety during the Butirosin biosynthesis, an aminoglycoside naturally synthesized by Niallia circulans (Bacillus circulans). This modification, which is unique among the aminoglycosides, assigns an evasion of resistance mechanisms in bacteria and inspired the development of Amikacin, a semisynthetic aminoglycoside largely used in chemotherapy. The AHBA formation is the result of seven proteins: BtrI, BtrJ, BtrK, BtrO, BtrU, BtrH and BtrG. Particularly in the biosynthesis of AHBA, BtrH is an acyltransferase that transfers this moiety from the peptidyl carrier protein BtrI to Ribostamycin as the penultimate steep of the pathway. However, how both proteins interact and how BtrH perform the catalysis AHBA transference to ribostamycin remain elusive. So, to comprehend the mechanisms of interaction between BtrH and BtrI needed for catalysis, structural studies involving crystallization and Nuclear Magnetic Resonance (NMR) techniques, with the design of probes to stabilize the complex, are proposed in this project. This methodology will be required for the structure determination of BtrI and the complex of BtrH-BtrI. However, we have already preliminary determined the structure of BtrH by X-ray diffraction. Due to its exclusivity, exploring this incorporation of AHBA moiety to Butirosin at its molecular level can be a valuable tool for combinatorial biosynthesis to produce novel aminoglycoside derivatives. (AU)