Structure-Guided Design, Synthesis, and Antivirulence Assessment of Covalent Staphylococcus aureus Sortase A Inhibitors

Sortase A (SrtA) is a membrane-associated cysteine transpeptidase required for bacterial virulence regulation and anchors surface proteins to cell wall, thereby assisting biofilm formation. SrtA is targeted in antivirulence treatments against Gram-positive bacterial infections. However, the development of potent small-molecule SrtA inhibitors is constrained owing to the limited understanding of the mode of action of inhibitors in the SrtA binding pocket. Herein, we designed and synthesized a novel class of covalent SrtA inhibitors based on the binding mode detailed in the X-ray crystal structure of the ML346/Streptococcus pyogenes SrtA complex. ML346 analog Y40 exhibited 2-fold increased inhibitory activity on Staphylococcus aureus SrtA and showed superior inhibitory effects on biofilm formation in vitro. Y40 protected Galleria mellonella larvae fromS. aureusinfections in vivo while minimally attenuating staphylococcal growth in vitro. Our study indicates that the covalent SrtA inhibitor Y40 is an antivirulence agent that is effective againstS. aureusinfections.

Covalent sortase A inhibitor ML346 prevents Staphylococcus aureus infection of Galleria mellonella

The housekeeping sortase A (SrtA), a membrane-associated cysteine transpeptidase, is responsible for anchoring surface proteins to the cell wall peptidoglycan in Gram-positive bacteria. This process is essential for the regulation of bacterial virulence and pathogenicity. Therefore, SrtA is considered to be an ideal target for antivirulence therapy. In this study, we report that ML346, a compound with a barbituric acid and cinnamaldehyde scaffold, functions as an irreversible inhibitor of Staphylococcus aureus SrtA (SaSrtA) and Streptococcus pyogenes SrtA (SpSrtA) in vitro at low micromolar concentrations. According to our X-ray crystal structure of the SpSrtAΔN81/ML346 complex (Protein Data Bank ID: 7V6K), ML346 covalently modifies the thiol group of Cys208 in the active site of SpSrtA. Importantly, ML346 significantly attenuated the virulence phenotypes of S. aureus and exhibited inhibitory effects on Galleria mellonella larva infection caused by S. aureus. Collectively, our results indicate that ML346 has potential for development as a covalent antivirulence agent for treating S. aureus infections, including methicillin-resistant S. aureus.

[Associations between pre-pregnancy body mass index and occurrence and clinical features of preeclampsia]

Objective: To investigate the associations between pre-pregnancy body mass index (BMI) and occurrence and clinical features in pregnant women complicated by preeclampsia (PE). Methods: We recruited 42 427 pregnant women who were diagnosed with intrauterine pregnancy at Shenzhen Maternity and Child Healthcare Hospital from July 2017 to December 2019, with a gestational age of 6~8⁺⁶ weeks, excluding those with basic diseases and incomplete medical records. Among them, 659 were diagnosed with PE. According to the pre-pregnancy BMI, the pregnant women were divided into underweight group (42 cases), normal body weight group (422 cases), overweight group (138 cases) and obesity group (57 cases). Maternal outcomes (the occurrence of preeclampsia, cesarean delivery rate) and neonatal outcomes (birth weight, Apgar score and neonatal ICU admission) were recorded. The maternal outcomes, gestational age of delivery, delivery mode, newborn birth weight, Apgar score and admission to neonatal ICU were compared among the pregnant women in each group. Logistic regression model was established to analyze the influence of different pre-pregnancy BMI on the occurrence and clinical features of PE. Results: The incidence of PE was 1.55% (659/42 427), and the incidence of PE was 0.61% (42/6 941), 1.44% (422/29 297), 2.62% (138/5 273) and 6.22% (57/916) in the underweight group, the normal weight group, the overweight group and the obesity group, respectively. After adjustment for age, parity, educational level, history of preeclampsia, and in vitro fertilization and embryo transfer (IVF-ET), compared with normal group, the adjusted OR for developing early-onset PE were 0.57 (95%CI: 0.29-1.02) for underweight, 1.03 (95%CI: 0.65-1.56) for overweight and 2.15 (95%CI: 1.03-4.02) for obesity groups. The OR for developing late-onset PE were 0.50 (95%CI: 0.33-0.72) for underweight, 1.57 (95%CI: 1.23-1.99) for overweight and 4.25 (95%CI: 3.00-5.91) for obesity group. The OR for PE without severe features were 0.54 (95%CI: 0.30-0.89), 1.40 (95%CI: 0.97-1.99) and 5.11 (95%CI: 3.22-7.84) for underweight, overweight and obesity groups, respectively. The OR for severe PE were 0.51 (95%CI: 0.33-0.75), 1.42 (95%CI: 1.10-1.83) and 2.97 (95%CI: 1.95-4.38) for underweight, overweight and obesity groups, respectively. The median neonate birth weight in women with PE were 2 420 g (1 602-2 845 g), 2 435 g (1 692-3 030 g), 2 540 g (1 922-3 132 g), and 2 950 g (2 050-3 360 g) for underweight, normal, overweight and obesity groups, respectively. The neonatal birth weight in obesity group was heavier than that in normal group (P<0.05). The incidence rates of large for gestational age (LGA) in PE women were 0 (0/42), 3.3% (14/422), 7.3% (10/138) and 17.5% (10/57) for underweight, normal, overweight and obesity groups, respectively. The incidence rate of LGA in obesity group was higher than that in normal group (P<0.05). Conclusions: Pre-pregnancy obesity is an independent risk factor for PE. Obesity related PE is more likely associated with late-onset PE and LGA. It is recommended to control weight before pregnancy, limit weight gain during pregnancy and control blood pressure to reduce the incidence of PE and ensure the safety of mother and child.

Tideglusib and Its Analogues As Inhibitors of Staphylococcus aureus SrtA

Sortase A (SrtA) anchors surface proteins to the cell wall envelope, and it has attracted increasing interesting as a potential antivirulence target. Several small-molecule inhibitors for SrtA have been developed, but target validation remains largely underexplored. Herein, we report a new class of SrtA inhibitors that supports antivirulence therapy through small-molecule targeting of SrtA. Tideglusib (TD), a drug candidate for myotonic dystrophy, was outstanding in high-throughput screening. A concise synthetic route quickly provided TD analogues, and the structure-activity relationships for SrtA inhibition have been established from those analogues. Several compounds largely retained the in vitro potency and exhibited a better solubility than TD. Additionally, TD attenuated virulence-related phenotypes in vitro and protected mice against lethal S. aureus USA300 bacteremia. Our study indicates that TD and its analogues could be new candidates as SrtA inhibitors with potential in the development of new antivirulence agents.