Re-Engineering Fungal Nonribosomal Peptide Synthetases by Module Dissection and Duplicated Thiolation Domains.

Unnatural product (uNP) nonribosomal peptides promise to be a valuable source of pharmacophores for drug discovery. However, the extremely large size and complexity of the nonribosomal peptide synthetase (NRPS) enzymes pose formidable challenges to the production of such uNPs by combinatorial biosynthesis and synthetic biology. Here we report a new NRPS dissection strategy that facilitates the engineering and heterologous production of these NRPSs. This strategy divides NRPSs into "splitting units", each forming an enzyme subunit that contains catalytically independent modules. Functional collaboration between the subunits is then facilitated by artificially duplicating, at the N-terminus of the downstream subunit, the linker - thiolation domain - linker fragment that is resident at the C-terminus of the upstream subunit. Using the suggested split site that follows a conserved motif in the linker connecting the adenylation and the thiolation domains allows cognate or chimeric splitting unit pairs to achieve productivities that match, and in many cases surpass those of hybrid chimeric enzymes, and even those of intact NRPSs, upon production in a heterologous chassis. Our strategy provides facile options for the rational engineering of fungal NRPSs and for the combinatorial reprogramming of nonribosomal peptide production.

The novel role of IFITM1-3 in myogenic differentiation of C2C12 cells.

Interferon-induced transmembrane proteins (IFITMs 1, 2, and 3) play a critical role in preventing pathogen infection in vertebrates. They are also involved in the occurrence and prognosis of cancer. Myogenesis is a complex process regulated by several factors. This study disclosed that Ifitm1-3 were upregulated in the process of myogenic differentiation of C2C12 myoblasts on days 3, 5, and 7. This positively correlated with the expression of differentiation factors MyoD, myogenin, Mrf5, and desmin. Furthermore, knockdown of Ifitm1-3 by their individual siRNAs inhibited myogenesis of C2C12 myoblasts, with relative downregulation of MyoD, myogenin, Mrf5, and desmin. Subsequently, myotube formation and fusion percentage decreased. Co-immunoprecipitation combined with LC-MS/MS analysis uncovered the interaction proteins of IFITM1 and IFITM3 in C2C12 myoblasts. A total of 84 overlapped interaction proteins of IFITM1 and IFITM3 were identified, and one of the clusters was engaged in cytoskeletal and sarcomere proteins, including desmin, myosin, actin, vimentin, nestin, ankycorbin, and nucleolin. Hence, we hypothesize that these interacting proteins may function as scaffolds for IFITM1-3, possibly through the interaction protein desmin to initiate further interaction with other proteins to participate in myogenesis; however, the molecular mechanisms remain unclear. Our study may contribute to the development of novel therapeutics for myopathic diseases.

[A Preliminary Exploration on the Pathogenesis of Osteopenia in Patients with Hemophilia].

OBJECTIVE: To investigate the influencing factors and pathogenesis of osteopenia in the patients with hemophilia. METHODS: Twenty-three patients with hemophilia were admitted in the hospital affiliated to North China University of Science and technology from March to August 2015, including 13 severe cases, 10 mild and moderate cases. All the patients accepted the detection of serum I collagen cross-linking N terminal peptide (NTX I), osteoprotegerin (OPG), bone alkaline phosphatase (BALP), basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF) and transforming growth factor-ß1 (TGF-ß1), the score scale of activity ability was recorded according to the criteria published by the U.S. Center for disease prevention and control in 2002, and 21 patients received the measurement of bone mineral density. According to the World Health Organization (WHO) definition, the clinical significance of bone mineral density (BMD) was assessed by measuring the Z level. RESULTS: Z level>-2 was recorded in 10 cases, Z≤-2 was recorded in 11 cases; the levels of body mass index (BMI) and human bone alkaline phosphatase (BALP) reflecting bone formation in 11 cases (Z≤-2) were lower than there in 10 cases (Z>-2) (P<0.05); the levels of BALP (r=0.489, P<0.05), IGF (r=0.538, P<0.05) and BMI (r=0.572, P<0.01) positively correlated significantly with BMD (P<0.05); the levels of bFGF (r=0.570, P<0.01) and OPG (r=0.505, P<0.05) positively correlated with NTX I, indicating bone destruction (P<0.05); the score of activity ability of severe patients was significantly lower than that of mild and moderate cases (P<0.05), BMD levels of these 2 groups were not statistically different (P>0.05). CONCLUSION: The BMD level does not correlate with the clinial grouping of hemophilia, the low body mass index may be a risk factor for bone lose; the mechanism of hemophilia patient's bone lose may be related with the decrease of osteogenic activity, the IGF can prevent bone lose in hemophilia, the bFGF and OPG can promote bone metabolism of the patients with hemophilia.