The bacteriophage LUZ24 "Igy" peptide inhibits the Pseudomonas DNA gyrase.

The bacterial DNA gyrase complex (GyrA/GyrB) plays a crucial role during DNA replication and serves as a target for multiple antibiotics, including the fluoroquinolones. Despite it being a valuable antibiotics target, resistance emergence by pathogens including Pseudomonas aeruginosa are proving problematic. Here, we describe Igy, a peptide inhibitor of gyrase, encoded by Pseudomonas bacteriophage LUZ24 and other members of the Bruynoghevirus genus. Igy (5.6 kDa) inhibits in vitro gyrase activity and interacts with the P. aeruginosa GyrB subunit, possibly by DNA mimicry, as indicated by a de novo model of the peptide and mutagenesis. In vivo, overproduction of Igy blocks DNA replication and leads to cell death also in fluoroquinolone-resistant bacterial isolates. These data highlight the potential of discovering phage-inspired leads for antibiotics development, supported by co-evolution, as Igy may serve as a scaffold for small molecule mimicry to target the DNA gyrase complex, without cross-resistance to existing molecules.

Identification and characterization of andalusicin: N-terminally dimethylated class III lantibiotic from Bacillus thuringiensis sv. andalousiensis.

Lanthipeptides, ribosomally synthesized and post-translationally modified peptides (RiPPs), can be divided into five classes based on their structures and biosynthetic pathways. Class I and II lanthipeptides have been well characterized, whereas less is known about members of the other three classes. Here, we describe a new family of class III lanthipeptides from Firmicutes. Members of the family are distinguished by the presence of a single carboxy-terminal labionin. We identified and characterized andalusicin, a representative of this family. Andalusicin bears two methyl groups at the α-amino terminus, a post-translational modification that has not previously been identified in class III lanthipeptides. Mature andalusicin A shows bioactivity against various Gram-positive bacteria, an activity that is highly dependent on the α-N dimethylation.

Allelic variation of the Tas1r3 taste receptor gene affects sweet taste responsiveness and metabolism of glucose in F1 mouse hybrids.

In mammals, inter- and intraspecies differences in consumption of sweeteners largely depend on allelic variation of the Tas1r3 gene (locus Sac) encoding the T1R3 protein, a sweet taste receptor subunit. To assess the influence of Tas1r3 polymorphisms on feeding behavior and metabolism, we examined the phenotype of F1 male hybrids obtained from crosses between the following inbred mouse strains: females from 129SvPasCrl (129S2) bearing the recessive Tas1r3 allele and males from either C57BL/6J (B6), carrying the dominant allele, or the Tas1r3-gene knockout strain C57BL/6J-Tas1r3tm1Rfm (B6-Tas1r3-/-). The hybrids 129S2B6F1 and 129S2B6-Tas1r3-/-F1 had identical background genotypes and different sets of Tas1r3 alleles. The effect of Tas1r3 hemizygosity was analyzed by comparing the parental strain B6 (Tas1r3 homozygote) and hemizygous F1 hybrids B6 × B6-Tas1r3-/-. Data showed that, in 129S2B6-Tas1r3-/-F1 hybrids, the reduction of glucose tolerance, along with lower consumption of and lower preference for sweeteners during the initial licking responses, is due to expression of the recessive Tas1r3 allele. Hemizygosity of Tas1r3 did not influence these behavioral and metabolic traits. However, the loss of the functional Tas1r3 allele was associated with a small decline in the long-term intake and preference for sweeteners and reduction of plasma insulin and body, liver, and fat mass.

Efficient in vivo synthesis of lasso peptide pseudomycoidin proceeds in the absence of both the leader and the leader peptidase.

Bacterial lasso peptides are made from linear ribosomally synthesized precursors by specific cleavage at the leader-core junction site of the precursor by a dedicated protease recognizing the leader, followed by cyclisation of the newly formed N-terminus of the core part with a side chain of the internal aspartic or glutamic residue catalyzed by a macrolactam synthetase. The resulting structure has a tail that is threaded and fixed inside the cycle formed. Here, we characterize a new lasso peptide, pseudomycoidin, encoded by Bacillus pseudomycoides DSM 12442. The most surprising and unique feature of pseudomycoidin is that it can be produced in vivo from the ribosomally synthesized core part by a macrolactam synthetase, in the absence of the leader protease. The minimalism of the pseudomycoidin synthesis system makes it a powerful model to generate pseudomycoidin-based lasso-peptide libraries and to study the poorly understood process of lasso formation. We detected two additional pseudomycoidin modifications: phosphorylation of a terminal residue that was previously observed in another lasso peptide, followed by glycosylation, which was not observed heretofore. We speculate that these bulky C-terminal modifications may help maintain the threaded lasso topology of the compound synthesized by the macrolactam synthetase.

Fertility-Sparing Treatment of Early Endometrial Cancer and Complex Atypical Hyperplasia in Young Women of Childbearing Potential.

OBJECTIVE: To evaluate oncologic and reproductive outcome with levonorgestrel-releasing intrauterine system combined with gonadotropin-releasing hormone agonist in women with grade 1 endometrial carcinoma, and the levonorgestrel monotherapy in women with complex atypical hyperplasia. MATERIALS/METHODS: A prospective study was conducted. We analyzed the clinical characteristics of 70 patients younger than 42 years (mean age, 33 years) with a diagnosis of complex atypical endometrial hyperplasia (AEH) or grade 1 endometrial adenocarcinoma who were treated with hormonal therapy at the Division of Gynecologic Oncology of P.A. Hertsen Moscow Cancer Research Institute from February 2009 to December 2012. Patients with complex AEH received monotherapy with levonorgestrel-releasing intrauterine system (Mirena, Shering, Finland; 52 mg). Patients with a diagnosis of grade 1 endometrial cancer were treated with levonorgestrel-releasing intrauterine system combined with gonadotropin-releasing hormone agonist (Zoladex; AstraZeneca UK Limited, UK; 3.6-mg depot). All the patients received hormonal therapy for a minimum of 6 months. Pretreatment evaluation consisted of transabdominal and transvaginal ultrasound in grayscale, color Doppler ultrasound, contrast-enhanced magnetic resonance imaging, cervical hysteroscopy, Pipelle endometrial biopsy, and morphological and immunohistochemical characteristics of the tissue. RESULTS: Seventy patients were included in study analyses. Twenty three (72%) of 32 patients with adenocarcinoma and 35 (92%) of 38 patients with AEH had complete remission, defined as the absence of any carcinoma or hyperplasia on endometrial sampling specimens. Among these cases, 2 patients with adenocarcinoma and 1 patient with AEH had recurrence after their complete response. Nine patients had persistent disease. Eight patients had 10 conceptions, resulting in 8 live births. CONCLUSIONS: The suggested conservative treatment strategy can be considered as a valid therapeutic option for young women of childbearing potential with atypical endometrial hyperplasia and grade 1 endometrial adenocarcinoma who wish to preserve their fertility and thus may be recommended as an alternative to hysterectomy. Close follow-up during and after the treatment period is strictly required.

Dietary glutamate signal evokes gastric juice excretion in dogs.

BACKGROUND: Dietary-free L-glutamate (Glu) in the stomach interacts with specific Glu receptors (T1R1/T1R3 and mGluR1-8) expressed on surface epithelial and gastric gland cells. Furthermore, luminal Glu activates the vagal afferents in the stomach through the paracrine cascade including nitric oxide and serotonin (5-HT). AIM: To elucidate the role of dietary Glu in neuroendocrine control of the gastrointestinal phase of gastric secretion. METHODS: In Pavlov or Heidenhain gastric pouch dogs, secretion was measured in the pouch while monosodium glutamate (MSG) was intubated into the main stomach alone or in combination with liquid diets. RESULTS: In both experimental models, supplementation of the amino acid-rich diet with MSG (100 mmol/l) enhanced secretions of acid, pepsinogen and fluid, and elevated plasma gastrin-17. However, MSG did not affect secretion stimulated by the carbohydrate-rich diet and had no effect on basal secretion when applied in aqueous solution. Effects of MSG were abolished by denervation of the stomach and proximal small intestine with intragastrically applied lidocaine and partially suppressed with the 5-HT(3) receptor blocker granisetron. CONCLUSIONS: Supplementation of amino acid-rich liquid diets with MSG enhances gastrointestinal phase secretion through neuroendocrine pathways which are partially mediated by 5-HT. Possible mechanisms are discussed.