The diversity of class D β-lactamases mediating resistance to β-lactams has been increasingly reported recently. In this study, a novel class D oxacillinase named OXA-830 was identified in a fully sequenced Aeromonas simiae strain, which was isolated from sewage discharged from a farm in southern China. OXA-830 shares the highest amino acid identity of 79.3% with an OXA-12-like variant named OXA-725. When expressed in E. coli DH5α, OXA-830 conferred resistance to penicillins and selected β-lactamase inhibitors but not to cephalosporins and carbapenems. Kinetic analysis of OXA-830 revealed a broad substrate profile including penicillins, cefazolin, cefoxitin, and ceftazidime but not carbapenems. The hydrolytic activity was significantly inhibited by sulbactam, followed by tazobactam, but was less effectively inhibited by clavulanic acid. The blaOXA–830 gene was located on the A. simiae A6 chromosome and the blaOXA–830-related region was bracketed by a pair of perfect inverted repeats.

To investigate the mechanisms of multiple resistance and the horizontal transfer of resistance genes in animal pathogens, we characterized the molecular structures of the resistance gene-related sequences in a multidrug-resistant Klebsiella pneumoniae strain R46 isolated from a rabbit. Molecular cloning was performed to clone the resistance genes, and minimum inhibitory concentrations (MICs) were measured to determine the resistance characteristics of the cloned genes and related strains. A conjugation experiment was conducted to assess the transferability of the resistance plasmids. Sequencing and comparative genomic methods were used to analyze the structures of the resistance gene-related sequences. The K. pneumoniae R46 genome consisted of a chromosome and three resistance plasmids named pR46-27, pR46-42, and pR46-270, respectively. The whole genome encoded 34 antibiotic resistance genes including a newly identified chromosome-encoded florfenicol resistance gene named mdfA2. pR46-270, besides encoding 26 antibiotic resistance genes, carried four clusters of heavy metal resistance genes and several virulence-related genes or gene clusters. The plasmid-encoded resistance genes were mostly associated with mobile genetic elements. The plasmid with the most similarity to the floR gene-harboring plasmid pR46-27 was pCTXM-2271, a plasmid from Escherichia coli. The results of this work demonstrated that the plasmids with multidrug resistance genes were present in animal-derived bacteria and more florfenicol resistance genes such as mdfA2 could be present in bacterial populations. The resistance genes encoded on the plasmids may spread between the bacteria of different species or genera and cause the resistance dissemination.

Delftia tsuruhatensis has become an emerging pathogen in humans. There is scant information on the genomic characteristics of this microorganism. In this study, we determined the complete genome sequence of a clinical D. tsuruhatensis strain, TR1180, isolated from a sputum specimen of a female patient in China in 2019. Phylogenetic and average nucleotide identity analysis demonstrated that TR1180 is a member of D. tsuruhatensis. TR1180 exhibited resistance to β-lactam, aminoglycoside, tetracycline and sulphonamide antibiotics, but was susceptible to phenicols, fluoroquinolones and macrolides. Its genome is a single, circular chromosome measuring 6,711,018 bp in size. Whole-genome analysis identified 17 antibiotic resistance-related genes, which match the antimicrobial susceptibility profile of this strain, as well as 24 potential virulence factors and a number of metal resistance genes. Our data showed that Delftia possessed an open pan-genome and the genes in the core genome contributed to the pathogenicity and resistance of Delftia strains. Comparative genomics analysis of TR1180 with other publicly available genomes of Delftia showed diverse genomic features among these strains. D. tsuruhatensis TR1180 harbored a unique 38-kb genomic island flanked by a pair of 29-bp direct repeats with the insertion of a novel In4-like integron containing most of the specific antibiotic resistance genes within the genome. This study reports the findings of a fully sequenced genome from clinical D. tsuruhatensis, which provide researchers and clinicians with valuable insights into this uncommon species.

Although endocrine therapies targeting estrogen receptor α (ERα) are effective in managing ER positive (+) breast cancer, many patients have primary resistance or develop resistance to endocrine therapies. In addition, ER+ breast cancer with PIK3CA activating mutations and 11q13-14 amplification have poor survival with unclear mechanism. We uncovered that higher expression of deubiquitinase USP35, located in 11q14.1, was associated with ER+ breast cancer and poor survival. Estrogen enhanced USP35 protein levels by downregulating USP35-targeting miRNA-140-3p and miRNA-26a-5p. USP35 promoted the growth of ER+ breast cancer in vitro and in vivo, and reduced the sensitivity of ER+ breast cancer cells to endocrine therapies such as tamoxifen and fulvestrant. Mechanistically, USP35 enhanced ERα stability by interacting and deubiquitinating ERα, and transcriptional activity of ERα by interacting with ERα in DNA regions containing estrogen response element. In addition, AKT, a key effector of PI3K, phosphorylated USP35 at Serine613, which promoted USP35 nuclear translocation, ERα transcriptional activity, and the growth of ER+ breast cancer cells. Our data indicate that USP35 and ERα form a positive feedback loop in promoting the growth of ER+ breast cancer. USP35 may be a treatment target for ER+ breast cancer with endocrine resistance or with PIK3CA mutations or hyperactivation of the PI3K pathway.

Bromodomain (BRD) proteins exhibit a variety of activities, such as histone modification, transcription factor recruitment, chromatin remodeling, and mediator or enhancer complex assembly, that affect transcription initiation and elongation. These proteins also participate in epigenetic regulation. Although specific epigenetic regulation plays an important role in the occurrence and development of cancer, the characteristics of the BRD family in renal clear cell carcinoma (KIRC) have not been determined. In this study, we investigated the expression of BRD family genes in KIRC at the transcriptome level and examined the relationship of the expression of these genes with patient overall survival. mRNA levels of tumor tissues and adjacent tissues were extracted from The Cancer Genome Atlas (TCGA) database. Seven BRD genes (KAT2A, KAT2B, SP140, BRD9, BRPF3, SMARCA2, and EP300) were searched by using LASSO Cox regression and the model with prognostic risk integration. The patients were divided into two groups: high risk and low risk. The combined analysis of these seven BRD genes showed a significant association with the high-risk groups and lower overall survival (OS). This analysis demonstrated that total survival could be predicted well in the low-risk group according to the time-dependent receiver operating characteristic (ROC) curve. The prognosis was determined to be consistent with that obtained using an independent dataset from TCGA. The relevant biological functions were identified using Gene Set Enrichment Analysis (GSEA). In summary, this study provides an optimized survival prediction model and promising data resources for further research investigating the role of the expression of BRD genes in KIRC.