Biology subjects

Grosse, C.

Publications and source records attributed to Grosse, C..

2 recordsLinked to original sources

bioRxiv2026

Structures and broad-spectrum growth-inhibiting activity of formomarinobactin, formylated marinobactin analogues from the Pseudomonas lutea clade

Pseudomonas graminis LMG 21661T, an environmental strain of the P. lutea clade, produces the siderophore formomarinobactin, a novel marinobactin-like siderophore. Mass spectrometry revealed that formomarinobactin shares the same six-residue peptide backbone as marinobactin but contains formylated rather than acetylated N-hydroxyornithines. Alike marinobactins, formomarinobactins are produced as a suite of siderophores with a conserved hexapeptide core but varying lipid tail lengths (C10-C14), shorter than the C12 to C18 characteristic of marinobactins. Both the biosynthesis and cognate receptor genes of the formomarinobactin system in P. graminis are iron regulated but unaffected by zinc or nickel underscoring their role in iron homeostasis. Genome mining combined with mass analyses demonstrated that formomarinobactin production is a conserved trait across the P. lutea clade, with one exception which appears to represent an intraspecific cheater that has lost siderophore production. Beyond the producing strains themselves, we identified a widespread distribution of putative formomarinobactin receptors among diverse Pseudomonas species, revealing a substantial capacity within the P. fluorescens super clade to pirate formomarinobactin as an iron source. Putative receptors were also found in genera outside the Pseudomonas genus. Growth stimulation assays confirmed functional formomarinobactin uptake in several Pseudomonas spp. and a Phytopseudomonas strain, with genetic validation in Pseudomonas rhodesiae. Importantly, formomarinobactin production confers more than a nutritional advantage. Members of the P. lutea clade producing formomarinobactin display pronounced growth inhibiting activity against a broad spectrum of clinical and environmental Gram-positive and with lower efficacy against Gram-negative bacteria. Purified formomarinobactin was able to inhibit growth under iron-limiting conditions and to a lesser extent in iron-rich conditions, highlighting a dual role for this molecule in both iron acquisition and microbial growth inhibition.

microbiology↗

bioRxiv2025

Exploiting Vitamin B6 Dependency: BVL3572S Inhibits HisC and AlaA to Kill Mycobacterium tuberculosis

Tuberculosis remains the leading cause of death from a single infectious agent worldwide, and the growing prevalence of multi-drug resistant Mycobacterium tuberculosis (Mtb) underscores the urgent need for antibiotics with novel mechanisms of action. Here, we characterize BVL3572S, a hydroxamic acid-containing compound that is bactericidal and potently inhibits the growth of both extracellular and intracellular Mtb. Integrated transcriptomic, genetic, and biochemical analyses identified the pyridoxal phosphate (PLP)-dependent aminotransferases HisC (Rv1600) and AlaA (Rv0337c; formerly AspC) as the primary molecular targets of BVL3572S, thereby simultaneously impacting L-histidine and L-alanine biosynthesis. Spontaneous resistance mutants harbored mutations in hisC or alaA. Target engagement was further supported by overexpression studies: AlaA overexpression increased resistance in the presence of L-His whereas HisC overexpression paradoxically increased susceptibility. X-ray crystallography revealed a covalent adduct between PLP and BVL3572S within the HisC active site. The short occupancy of this adduct suggests a futile cycle that sequesters PLP. Isotopic labeling revealed widespread perturbation of amino acid biosynthesis, consistent with PLP starvation. The stepwise resistance observed upon supplementation with L-His and L-Ala together or with PLP alone suggests inhibition of multiple targets. Genome-scale CRISPRi and Tn-seq analyses additionally indicated disruptions in central metabolism, cell envelope integrity, and redox balance, possibly due to PLP depletion cascades. Consistent with its inhibition of AlaA, BVL3572S displayed strong synergy with D-cycloserine, a second-line antitubercular drug targeting D-alanine synthesis and impacting peptidoglycan synthesis, highlighting the potential of this compound in combination therapy. Collectively, our findings establish BVL3572S as a promising lead compound acting through a previously unexploited, multitarget mechanism that induces broad metabolic stress in Mtb, offering a novel therapeutic strategy against drug-resistant tuberculosis.

microbiology↗