Biology subjects

Temple, B. R. S.

Publications and source records attributed to Temple, B. R. S..

2 recordsLinked to original sources

bioRxiv2022

Dynamics of allosteric regulation of the phospholipase C-γ isozymes upon recruitment to membranes

Numerous receptor tyrosine kinases and immune receptors activate phospholipase C-gamma (PLC-{gamma}) isozymes at membranes to control diverse cellular processes including phagocytosis, migration, proliferation, and differentiation. The molecular details of this process are not well understood. Using hydrogen-deuterium exchange mass spectrometry (HDX-MS), we show that PLC-{gamma}1 is relatively inert to lipid vesicles that contain its substrate, PIP2, unless first bound to the kinase domain of the fibroblast growth factor receptor (FGFR1). Exchange occurs throughout PLC-{gamma}1 and is exaggerated in PLC-{gamma}1 containing an oncogenic substitution (D1165H) that allosterically activates the lipase. These data support a model whereby initial complex formation shifts the conformational equilibrium of PLC-{gamma}1 to favor activation. This receptor-induced priming of PLC-{gamma}1 also explains the capacity of a kinase-inactive fragment of FGFR1 to modestly enhance the lipase activity of PLC-{gamma}1 operating on lipid vesicles but not a soluble analog of PIP2 and highlights cooperativity between receptor engagement and membrane proximity. Priming is expected to be greatly enhanced for receptors embedded in membranes and nearly universal for the myriad of receptors and co-receptors that bind the PLC-{gamma} isozymes.

biochemistry↗

bioRxiv2022

Distinct developmental phenotypes result from mutation of Set8/KMT5A and histone H4 lysine 20 in Drosophila melanogaster

Mono-methylation of histone H4 lysine 20 (H4K20me1) is catalyzed by Set8/KMT5A and regulates numerous aspects of genome organization and function. Loss-of-function mutations in Drosophila melanogaster Set8 or mammalian KMT5A prevent H4K20me1 and disrupt development. Set8/KMT5A also has non-histone substrates, making it difficult to determine which developmental functions of Set8/KMT5A are attributable to H4K20me1 and which to other substrates or to non-catalytic roles. Here, we show that human KMT5A can functionally substitute for Set8 during Drosophila development and that the catalytic SET domains of the two enzymes are fully interchangeable. We also uncovered a role in eye development for the N-terminal domain of Set8 that cannot be complemented by human KMT5A. Whereas Set8null mutants are inviable, we found that an R634G mutation in the SET domain predicted to ablate catalytic activity resulted in viable adults, suggesting important non-catalytic functions of Set8. Similarly, flies that were engineered to express only unmodifiable H4 histones (H4K20A) can also complete development, but they are phenotypically distinct from H4K20R, Set8null, and Set8R634G animals. Taken together, our results demonstrate functional conservation of KMT5A and Set8 enzymes, as well as distinct roles for Set8 and H4K20me1 in Drosophila development.

genetics↗