1. Expression and protease characterization of a conserved protein YgjD in Vibrio harveyi
Yayuan Zhang, Jixiang Chen, Yonggang Wang, Yanlin Li, Wenhong Rui, Jiyi Zhang, Dan Luo PeerJ. 2020 May 18;8:e9061. doi: 10.7717/peerj.9061. eCollection 2020.
The glycopeptidase GCP and its homologue proteins are conserved and essential for survival of bacteria. The ygjD gene (Glycopeptidase homologue) was cloned from Vibrio harveyi strain SF-1. The gene consisted of 1,017 bp, which encodes a 338 amino acid polypeptide. The nucleotide sequence similarity of the ygjD gene with that of V. harveyi FDAARGOS 107 was 95%. The ygjD gene also showed similarities of 68%, 67% and 50% with those of Salmonella enterica, Escherichia coli and Bacillus cereus. The ygjD gene was expressed in E. coli BL21 (DE3) and the recombinant YgjD was purified by Ni2+ affinity chromatography column. The purified YgjD showed a specific 37 kDa band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and exhibited protease activities of 59,000 units/mg, 53,700 units/mg and 8,100 units/mg, respectively, on N-Acetyl-L-tyrosine ethyl ester monohydrate (ATEE), N-Benzoyl-L-tyrosine ethyl ester (BTEE) and N-Benzoyl-DL-arginine-4-nitroanilide hydrochloride (BAPNA) substrates. When the conserved amino acids of His111, Glu113 and His115 in the YgjD were replaced with alanine, respectively, the protease activities of the mutants were partly decreased. The two conserved His111 and His115 of YgjD were mutated and the protein lost the protease activity, which implied that the two amino acid played very important roles in maintaining its protease activity. The addition of the purified YgjD to the culture medium of V. harveyi strain SF-1 can effectively promote the bacteria growth. These results indicated that the protease activities may be involved in the survival of bacteria.
2. On-a-chip tryptic digestion of transthyretin: a step toward an integrated microfluidic system for the follow-up of familial transthyretin amyloidosis
Jeanne Bataille, et al. Analyst. 2018 Feb 26;143(5):1077-1086. doi: 10.1039/c7an01737e.
A microfluidic microreactor for trypsin mediated transthyretin (TTR) digestion has been developed as a step towards the elaboration of a fully integrated microdevice for the detection of a rare and disabling disease, the familial transthyretin amyloidosis (ATTR) which is related to specific TTR mutations. Therefore, an enzymatic microreactor coupled to an analytical step able to monitor the mutation of TTR on specific peptide fragments would allow an accurate monitoring of the treatment efficiency of ATTR. In this study, two types of immobilized trypsin microreactors have been investigated: a new miniaturized, microfluidic fluidized bed packed with trypsin functionalized magnetic particles (MPs), and a thiol-ene (TE) monolith-based chip. Their performances were first demonstrated with N-benzoyl-dl-arginine-4-nitroanilide hydrochloride BApNA, a low molecular weight substrate. High reaction yields (75.2%) have been reached within 0.6 min for the TE-based trypsin microreactor, while a lower yield (12.4%) was obtained for the micro-fluidized bed within a similar residence time. Transposition of the optimized conditions, developed with BApNA, to TTR digestion in the TE-based trypsin microreactor was successfully performed. We demonstrated that the TE-chip can achieve an efficient and reproducible digestion of TTR. This has been assessed by MS detection. In addition, TTR hydrolysis led to the production of a fragment of interest allowing the therapeutic follow-up of more than twenty possible ATTR mutations. High sequence coverage (90%), similar to those obtained with free trypsin, was achieved in a short time (2.4 min). Repeated experiments showed good reproducibility (RSD = 6.8%). These promising results open up the route for an innovative treatment follow-up dedicated to ATTR.
