XAC4296 Is a Multifunctional and Exclusive Xanthomonadaceae Gene Containing a Fusion of Lytic Transglycosylase and Epimerase Domains

• Published in: Microorganisms (Basel) Vol. 10; no. 5; p. 1008
• Main Authors: de Oliveira, Amanda C P, Ferreira, Rafael M, Ferro, Maria Inês T, Ferro, Jesus A, Zamuner, Caio, Ferreira, Henrique, Varani, Alessandro M
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 11.05.2022; MDPI
• Subjects: Aldose 1-epimerase; Amino acids; Ampicillin; Antibiotics; Antimicrobial resistance; Biosynthesis; Canker; Carbon; Cell division; cell wall synthesis; Cell walls; Cellular biology; Chromosomes; citrus canker; DNA polymerase; Domains; E coli; Enzymes; Epimerase; Etiology; Gene fusion; Genomes; Glutamic acid; Metabolism; Microorganisms; multi-domains enzymes; Mutants; Peptidoglycans; Phenotypes; Proteins; Sucrose; Virulence; Xanthomonadaceae; Xanthomonas citri; β-Lactam antibiotics; United Kingdom > UK; England; United States > US; multi-domains enzymes; Xanthomonas citri; citrus canker; cell wall synthesis; antimicrobial resistance; gene fusion
• ISSN: 2076-2607; 2076-2607
• DOI: 10.3390/microorganisms10051008

Microorganisms have a limited and highly adaptable repertoire of genes capable of encoding proteins containing single or variable multidomains. The phytopathogenic bacteria subsp. ( ) ( family), the etiological agent of Citrus Canker (CC), presents a collection of multidomain and multifunctional enzymes (MFEs) that remains to be explored. Recent studies have shown that multidomain enzymes that act on the metabolism of the peptidoglycan and bacterial cell wall, belonging to the Lytic Transglycosylases (LTs) superfamily, play an essential role in biology. One of these LTs, named XAC4296, apart from the Transglycosylase SLT_2 and Peptidoglycan binding-like domains, contains an unexpected aldose 1-epimerase domain linked to the central metabolism; therefore, resembling a canonical MFE. In this work, we experimentally characterized XAC4296 revealing its role as an MFE and demonstrating its probable gene fusion origin and evolutionary history. The XAC4296 is expressed during plant-pathogen interaction, and the Δ4296 mutant impacts CC progression. Moreover, Δ4296 exhibited chromosome segregation and cell division errors, and sensitivity to ampicillin, suggesting not only LT activity but also that the XAC4296 may also contribute to resistance to β-lactams. However, both Δ4296 phenotypes can be restored when the mutant is supplemented with sucrose or glutamic acid as a carbon and nitrogen source, respectively; therefore, supporting the epimerase domain's functional relationship with the central carbon and cell wall metabolism. Taken together, these results elucidate the role of XAC4296 as an MFE in , also bringing new insights into the evolution of multidomain proteins and antimicrobial resistance in the family.