The Crystal Structure of Rv1347c, a Putative Antibiotic Resistance Protein from Mycobacterium tuberculosis, Reveals a GCN5-related Fold and Suggests an Alternative Function in Siderophore Biosynthesis

Abstract

Mycobacterium tuberculosis, the cause of tuberculosis, is a devastating human pathogen. The emergence of multidrug resistance in recent years has prompted a search for new drug targets and for a better understanding of mechanisms of resistance. Here we focus on the gene product of an open reading frame from M. tuberculosis, Rv1347c, which is annotated as a putative aminoglycoside N-acetyltransferase. The Rv1347c protein does not show this activity, however, and we show from its crystal structure, coupled with functional and bioinformatic data, that its most likely role is in the biosynthesis of mycobactin, the M. tuberculosis siderophore. The crystal structure of Rv1347c was determined by multiwavelength anomalous diffraction phasing from selenomethionine-substituted protein and refined at 2.2 Å resolution (r ‫؍‬ 0.227, R free ‫؍‬ 0.257). The protein is monomeric, with a fold that places it in the GCN5-related N-acetyltransferase (GNAT) family of acyltransferases. Features of the structure are an acylCoA binding site that is shared with other GNAT family members and an adjacent hydrophobic channel leading to the surface that could accommodate long-chain acyl groups. Modeling the postulated substrate, the N ⑀

Antitubercular Nucleosides That Inhibit Siderophore Biosynthesis: SAR of the Glycosyl Domain

“…16 Additional modifications through lipidation (catalyzed by MbtK) and Nhydroxylation (catalyzed by MbtG) of the lysine residues provides the mycobactins. 17,32,33 The second biosynthetic step, catalyzed by MbtA, is an attractive point to block for the following reasons. First, the adenylating enzyme MbtA is a member of the well-studied adenylate-forming enzyme superfamily, and inhibitors of the functionally related aminoacyl tRNA synthetases have already been developed and are used clinically (e.g.…”

Structural and Functional Characterization of an RNase HI Domain from the Bifunctional Protein Rv2228c from Mycobacterium tuberculosis

“…The sequencing and annotation of the M. tuberculosis genome (9) have enabled a fuller evaluation of the biology of this important human pathogen and the identification of new potential targets for anti-TB drug discovery, although annotations are potentially compromised by the absence of direct structural or functional data (5). Some examples of misannotations have already been noted (6,20,46).…”

Identification of an ABC Transporter Required for Iron Acquisition and Virulence inMycobacterium tuberculosis

“…According to the TubercuList web site (genolist.pasteur.fr /TubercuList) Rv1344 encodes a probable acyl-carrier protein and Rv1346 protein is a possible acyl-coenzyme A dehydrogenase (FadE14). Rv1345 and Rv1347 are annotated to encode proteins of unknown function; however, recent studies suggest that the products of these genes might participate in siderophore synthesis (1,5). The last two genes in this cluster, Rv1348 and Rv1349, encode an ABC transporter (2) highly similar to the YbtPQ system of Yersinia pestis (7).…”