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Osteogenic growth peptide (OGP) was characterized in regenerating bone marrow, which can increase osteogenesis and hematopoiesis. The carboxy-terminal pentapeptide is a naturally occurring human and murine mitogen equipotent to OGP. In this study, we evaluated the potential role of OGP10-14 in regulation of hematopoiesis in human hematopoietic stem cells and animal model. Our results showed CD34+ stem cells from umbilical cord blood (UBC) were significantly increased in OGP10-14 treated samples, which is nearly equivalent to the results obtained from the combinations of IL3, IL11, G-CSF, and EPO group. OGP10-14 can also stimulate the differentiation of stem cells from bone marrow at the level of noncommitted progenitor stem cells, thus increasing the number of reconstituted red and white cells as well as platelets after injected i.m. everyday continuing for 5 days in hematopoietic function damage mice comparing with the OGP-untreated group. These data implicate that the role of OGP10-14 regulating hematopoiesis is in the early stage of the whole hematopoietic growth factors (HGFs) regulating network, just like the position of interleukin 13 in the hematopoiesis network.

Protein biotinylation, a rare form of post-translational modification, is found in enzymes required for lipid biosynthesis. In mycobacteria, this process is essential for the formation of their complex and distinct cell wall and has become a focal point of drug discovery approaches. The enzyme responsible for this process, biotin protein ligase, substantially varies in different species in terms of overall structural organization, regulation of function and substrate specificity. To advance the understanding of the molecular mechanism of biotinylation in Mycobacterium tuberculosis we have biochemically and structurally characterized the corresponding enzyme. We report the high-resolution crystal structures of the apo-form and reaction intermediate biotinyl-5'-AMP-bound form of M. tuberculosis biotin protein ligase. Binding of the reaction intermediate leads to clear disorder-to-order transitions. We show that a conserved lysine, Lys138, in the active site is essential for biotinylation.