ABSTRACT
Pichia pastoris is the widely used expression system for producing recombinant secretory proteins. It is known that Kex2 protease plays a vital role in the process of protein secretion, in which the P1' site affects its cleavage efficiency. To enhance the expression level of fungal defensin-derived peptide NZ2114, this work attempts to optimize the P1' site of Kex2 by replacing it with 20 amino acids in turn. The results showed that when the amino acid of the P1' site was changed to Phe (F), the yield of target peptide significantly increased from 2.39 g/L to 4.81 g/L. Additionally, the novel peptide F-NZ2114 (short for FNZ) showed strong antimicrobial activity against Gram-positive (G+) bacteria, especially for Staphylococcus aureus and Streptococcus agalactiae (MIC: 4-8 µg/mL). The FNZ was very stable and retained high activity in various conditions; in addition, a low cytotoxicity and no hemolysis were observed even at a high concentration of 128 µg/mL, and a longer postantibiotic effect was reached. The above results indicate that this engineering strategy provided a feasible optimization scheme for enhancing the expression level and druggability of this antimicrobial peptide from fungal defensin and other similar targets by this updated recombinant yeast.
ABSTRACT
Objective: The purpose of this study was to identify trajectories of body mass index (BMI) in toddlers from birth to 2 years old and examine their association with infantile overweight/obesity. Methods: Data were collected from 19,054 children born in any hospital or community healthcare center in Taizhou, China from 2018 to 2019 with at least three BMI measurements after birth. The Latent Class Growth Mixture Model was used to identify distinct BMI trajectories during the first 2 years of infants. Multiple logistic regression models were conducted to explore the associated factors of different BMI trajectories, and log-binomial regression was performed to assess the association between the trajectories and overweight/obesity. Results: Three heterogeneous BMI trajectories were identified and labeled as "lower" (36.21%, n = 6,899), "middle" (53.15%, n = 10,128) and "upper" (10.64%, n = 2,027), respectively. Several characteristics of infants and their corresponding mothers were found to be correlated with infant BMI trajectories, including infant sex, mode of delivery and weight at birth, as well as maternal parity, early pregnancy BMI and status of gestational diabetes mellitus. Furthermore, compared with those in the lower trajectory, infants in the middle [prevalence ratio (PR) = 2.63, 95% confidence interval (95%CI) = 2.17-2.63] or upper (PR = 2.98, 95%CI = 1.51-2.98) trajectory groups were prone to be overweight/obesity at their final observation. Conclusion: Heterogeneous BMI trajectories were observed in our study. Characteristics of both infants and their corresponding mothers could be potential determinants of infant growth. Moreover, infants in the middle and upper trajectory groups were more likely to suffer overweight/obesity.