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Ficellomycin is an aziridine antibiotic produced by Streptomyces ficellus, which displays high in vitro activity against Gram-positive bacteria including multidrug resistant strains of Staphylococcus aureus. Compared to currently available antibiotics, ficellomycin exhibits a unique mechanism of action—it impairs the semiconservative DNA replication by inducing the formation of deficient 34S DNA fragments, which lack the ability to integrate into larger DNA pieces and eventually the complete bacterial chromosome. Until recently, some important progress has been made in research on ficellomycin synthesis and biosynthesis, opening the perspective to develop a new generation of antibiotics with better clinical performance than the currently used ones. In this review, we will cover the discovery and biological activity of ficellomycin, its biosynthesis, mode of action, and related synthetic analogs. The role of ficellomycin and its analogs as an important source of drug prototypes will be discussed together with future research prospects. [ABSTRACT FROM AUTHOR]

Ficellomycin is a peptide-like antibiotic which exhibits potent in vitro activity against Penicillium oxalicum and Staphylococcus aureus, even against strains resistant to most clinically used antibiotics. The gene cluster responsible for ficellomycin biosynthesis was cloned from Streptomyces ficellus and sequenced. It was found to contain 26 ORFs and is located within 30 kb of contiguous DNA. Targeted disruption of the encoding genes revealed that most were involved in the functional section of ficellomycin biosynthesis, such as peptide assembly, regulation, resistance, and biosynthesis of the precursor of ficellomycin 2-[4-guanidyl-1-azabicyclo[3.1.0]hexan-2-yl] glycine (2-GAHG). Within the 2-GAHG synthesis pathway, a sulfate adenylyltransferase appears to be involved in the synthesis of the pharmaceutically important 1-azabicyclo[3.1.0]hexane ring moiety, which has been reported to cause DNA cross-linking or impairment of semiconservative DNA replication. [ABSTRACT FROM AUTHOR]

Streptococcus zooepidemicus is a bacterial pathogen used for production of hyaluronan in industry. Intensive research has significantly contributed to our understanding of S. zooepidemicus biology and pathogenesis. However, the lack of an effective targeted gene inactivation system in S. zooepidemicus has notably prevented the functional genomics analysis of this gram-positive bacterium. Here, we report the development of a markerless gene deletion system in S. zooepidemicus. We constructed a sacB expression cassette on the thermosensitive suicide vector pSET4s and demonstrated its use as a counterselection marker in S. zooepidemicus. We validated the efficiency of this system by deletion of hasA, which synthesizes the important virulence factor hyaluronic acid (HA) capsule. The genotype of the resultant hasA mutant was confirmed by polymerase chain reaction and sequencing. Deletion of hasA resulted in non-mucoid morphology, loss of HA capsule formation, and HA production. These defects can be rescued by introduction of a plasmid containing wild-type hasA expression cassette. Moreover, compared with wild type, hasA mutant showed no significant difference in expressions of other members of the hasABCDE operon, further suggesting that the loss of hasA contributed to the defects observed with Δ hasA mutant. Our results describe the first establishment of a sacB-based counterselection system in S. zooepidemicus, along with the first demonstration of hasA that is the only gene encoding a functional hyaluronan synthase in this bacterium. [ABSTRACT FROM AUTHOR]