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The dialkyl-ortho-biaryl class of phosphines, commonly known as Buchwald-type ligands, are among the most important phosphines in Pd-catalyzed cross-coupling. These ligands have also been successfully applied to several synthetically valuable Ni-catalyzed cross-coupling methodologies and, as demonstrated in this work, are top performing ligands in Ni-catalyzed Suzuki Miyaura Coupling (SMC) and C-N coupling reactions, even outperforming commonly employed bisphosphines like dppf in many circumstances. However, little is known about their structure-reactivity relationships (SRRs) with Ni, and limited examples of well-defined, catalytically relevant Ni complexes with Buchwald-type ligands exist. In this work, we report the analysis of Buchwald-type phosphine SRRs in four representative Ni-catalyzed cross-coupling reactions. Our study was guided by data-driven classification analysis, which together with mechanistic organometallic studies of structurally characterized Ni(0), Ni(I), and Ni(II) complexes allowed us to rationalize reactivity patterns in catalysis. Overall, we expect that this study will serve as a platform for further exploration of this ligand class in organonickel chemistry as well as in the development of new Ni-catalyzed cross-coupling methodologies.

Many pathogenic bacteria, including Streptococcus gordonii, possess a pathway for the cellular export of a single serine-rich-repeat protein that mediates the adhesion of bacteria to host cells and the extracellular matrix. This adhesin protein is O-glycosylated by several cytosolic glycosyltransferases and requires three accessory Sec proteins (Asp1-3) for export, but how the adhesin protein is processed for export is not well understood. Here, we report that the S. gordonii adhesin GspB is sequentially O-glycosylated by three enzymes (GtfA/B, Nss, and Gly) that attach N-acetylglucosamine and glucose to Ser/Thr residues. We also found that modified GspB is transferred from the last glycosyltransferase to the Asp1/2/3 complex. Crystal structures revealed that both Asp1 and Asp3 are related to carbohydrate-binding proteins, suggesting that they interact with carbohydrates and bind glycosylated adhesin, a notion that was supported by further analyses. We further observed that Asp1 also has an affinity for phospholipids, which is attenuated by Asp2. In summary, our findings support a model in which the GspB adhesin is sequentially glycosylated by GtfA/B, Nss, and Gly and then transferred to the Asp1/2/3 complex in which Asp1 mediates the interaction of the Asp1/2/3 complex with the lipid bilayer for targeting of matured GspB to the export machinery.

Objectives: Elimination of brain tumour initiating cells (BTICs) is important for the good prognosis of malignant brain tumour treatment. To develop a novel strategy targeting BTICs, we studied NR2E1(TLX) involved self‐renewal mechanism of BTICs and explored the intervention means. Materials and Methods: NR2E1 and its interacting protein‐LSD1 in BTICs were studied by gene interference combined with cell growth, tumour sphere formation, co‐immunoprecipitation and chromatin immunoprecipitation assays. NR2E1 interacting peptide of LSD1 was identified by Amide Hydrogen/Deuterium Exchange and Mass Spectrometry (HDX‐MS) and analysed by in vitro functional assays. The in vivo function of the peptide was examined with intracranial mouse model by transplanting patient‐derived BTICs. Results: We found NR2E1 recruits LSD1, a lysine demethylase, to demethylate mono‐ and di‐methylated histone 3 Lys4 (H3K4me/me2) at the Pten promoter and repress its expression, thereby promoting BTIC proliferation. Using Amide Hydrogen/Deuterium Exchange and Mass Spectrometry (HDX‐MS) method, we identified four LSD1 peptides that may interact with NR2E1. One of the peptides, LSD1‐197‐211 that locates at the LSD1 SWIRM domain, strongly inhibited BTIC proliferation by promoting Pten expression through interfering NR2E1 and LSD1 function. Furthermore, overexpression of this peptide in human BTICs can inhibit intracranial tumour formation. Conclusion: Peptide LSD1‐197‐211 can repress BTICs by interfering the synergistic function of NR2E1 and LSD1 and may be a promising lead peptide for brain tumour therapy in future. [ABSTRACT FROM AUTHOR]

All kingdoms of life produce essential nicotinamide dinucleotide NADP(H) using NAD kinases (NADKs). A panel of published NADK structures from bacteria, eukaryotic cytosol, and yeast mitochondria revealed similar tetrameric enzymes. Here, we present the 2.8-Å structure of the human mitochondrial kinase NADK2 with a bound substrate, which is an exception to this uniformity, diverging both structurally and biochemically from NADKs. We show that NADK2 harbors a unique tetramer disruptor/dimerization element, which is conserved in mitochondrial kinases of animals (EMKA) and absent from other NADKs. EMKA stabilizes the NADK2 dimer but prevents further NADK2 oligomerization by blocking the tetramerization interface. This structural change bears functional consequences and alters the activation mechanism of the enzyme. Whereas tetrameric NADKs undergo cooperative activation via oligomerization, NADK2 is a constitutively active noncooperative dimer. Thus, our data point to a unique regulation of NADP(H) synthesis in animal mitochondria achieved via structural adaptation of the NADK2 kinase. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2009.11.002 Byline: Yi Ren (1), Calvin K. Yip (2), Arati Tripathi (1), David Huie (1), Philip D. Jeffrey (1), Thomas Walz (2)(3), Frederick M. Hughson (1) Keywords: CELLBIO Abstract: Vesicle trafficking requires membrane fusion, mediated by SNARE proteins, and upstream events that probably include 'tethering,' an initial long-range attachment between a vesicle and its target organelle. Among the factors proposed to mediate tethering are a set of multisubunit tethering complexes (MTCs). The Dsl1 complex, with only three subunits, is the simplest known MTC and is essential for the retrograde traffic of COPI-coated vesicles from the Golgi to the ER. To elucidate structural principles underlying MTC function, we have determined the structure of the Dsl1 complex, revealing a tower containing at its base the binding sites for two ER SNAREs and at its tip a flexible lasso for capturing vesicles. The Dsl1 complex binds to individual SNAREs via their N-terminal regulatory domains and also to assembled SNARE complexes; moreover, it is capable of accelerating SNARE complex assembly. Our results suggest that even the simplest MTC may be capable of orchestrating vesicle capture, uncoating, and fusion. Author Affiliation: (1) Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA (2) Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA (3) Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA Article History: Received 2 August 2009; Revised 19 October 2009; Accepted 2 November 2009 Article Note: (miscellaneous) Published: December 10, 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2008.02.041 Byline: Yongna Xing (1), Zhu Li (1), Yu Chen (1), Jeffry B. Stock (1), Philip D. Jeffrey (1), Yigong Shi (1) Keywords: PROTEINS; SIGNALING Abstract: Protein phosphatase 2A (PP2A) is an important serine/threonine phosphatase that plays a role in many biological processes. Reversible carboxyl methylation of the PP2A catalytic subunit is an essential regulatory mechanism for its function. Demethylation and negative regulation of PP2A is mediated by a PP2A-specific methylesterase PME-1, which is conserved from yeast to humans. However, the underlying mechanism of PME-1 function remains enigmatic. Here we report the crystal structures of PME-1 by itself and in complex with a PP2A heterodimeric core enzyme. The structures reveal that PME-1 directly binds to the active site of PP2A and that this interaction results in the activation of PME-1 by rearranging the catalytic triad into an active conformation. Strikingly, these interactions also lead to inactivation of PP2A by evicting the manganese ions that are required for the phosphatase activity of PP2A. These observations identify a dual role of PME-1 that regulates PP2A activation, methylation, and holoenzyme assembly in cells. Author Affiliation: (1) Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Princeton, NJ 08544, USA Article History: Received 29 November 2007; Revised 14 January 2008; Accepted 8 February 2008 Article Note: (miscellaneous) Published: April 3, 2008

Carbonic anhydrase, a zinc enzyme found in organisms from all kingdoms, catalyses the reversible hydration of carbon dioxide and is used for inorganic carbon acquisition by phytoplankton. In the oceans, [...]

The crystal structures of the protein phosphatase 2A (PP2A) core enzyme bound to two of its inhibitors, the tumor-inducing agents okadaic acid and microcystin-LR, at 2.6 and 2.8 Angstrom resolution respectively are reported. The scaffolding subunit exhibits considerable conformational flexibility, which is proposed to play an important role in PP2A function.

Author(s): Ning Zheng [1, 2]; Brenda A. Schulman [1, 3]; Langzhou Song [1, 2]; Julie J. Miller [1, 2]; Philip D. Jeffrey [1]; Ping Wang [1, 2]; Claire Chu [3]; [...]

Research has been conducted on the Brca1 C-terminal domains, protein-protein interaction motif in the proteins involved in the DNA damage response and DNA repair. The structures of the human 53BP1-p53 complex and of the rat Brac1 BRCT repeats are described.

Results reveal that INK4 inhibitor binding to the cyclin-dependent kinases 4 and 6 weakens the affinity of D-type cyclins to the enzyme as shown by the enzyme-cyclin-inhibitor complex crystal structure analysis. Data point out that the inhibition results from distortion of the ATP binding site and misalignment of catalytic residues.

Author(s): Brenda A. Schulman [1]; Andrea C. Carrano [2]; Philip D. Jeffrey [1]; Zachary Bowen [1]; Elspeth R. E. Kinnucan [1]; Michael S. Finnin [1, 4]; Stephen J. Elledge [3, [...]