Molecular basis for polysaccharide recognition and modulated ATP hydrolysis by the O antigen ABC transporter.

O antigens are ubiquitous protective extensions of lipopolysaccharides in the extracellular leaflet of the Gram-negative outer membrane. Following biosynthesis in the cytosol, the lipid-linked polysaccharide is transported to the periplasm by the WzmWzt ABC transporter. Often, O antigen secretion requires the chemical modification of its elongating terminus, which the transporter recognizes via a carbohydrate-binding domain (CBD).

Sperm chromatin-condensing protamine enhances SMYD5 thermal stability.

Studying thermal stability of proteins not only provides insight into protein structure but also is instrumental in identifying previously unknown interaction partners. We develop a machine learning strategy that combines orthogonal partial least squares regression and stability screening of Silver Bullets Bio library to identify biologically active molecules that enhance protein stability. This strategy proves effective in extracting the stability-enhancing molecules for SMYD5, a histone lysine methyltransferase that regulates chromosome integrity.

Biosynthesis and Export of Bacterial Glycolipids.

Complex carbohydrates are essential for many biological processes, from protein quality control to cell recognition, energy storage, and cell wall formation. Many of these processes are performed in topologically extracellular compartments or on the cell surface; hence, diverse secretion systems evolved to transport the hydrophilic molecules to their sites of action. Polyprenyl lipids serve as ubiquitous anchors and facilitators of these transport processes.

Structural and Antiviral Studies of the Human Norovirus GII.4 Protease.

Norovirus is the leading cause of acute gastroenteritis worldwide with a yearly reported 700 million cases driving a $60 billion global socioeconomic burden. With no United States Food and Drug Administration approved therapeutics and the chance for severe chronic infection and life-threatening complications, researchers have identified the protease as a potential target. However, drug development has focused on the norovirus GI.

A functional proteomics platform to reveal the sequence determinants of lysine methyltransferase substrate selectivity.

Lysine methylation is a key regulator of histone protein function. Beyond histones, few connections have been made to the enzymes responsible for the deposition of these posttranslational modifications. Here, we debut a high-throughput functional proteomics platform that maps the sequence determinants of lysine methyltransferase (KMT) substrate selectivity without a priori knowledge of a substrate or target proteome.

SAXS analysis of a soluble cytosolic NgBR construct including extracellular and transmembrane domains.

The Nogo-B receptor (NgBR) is involved in oncogenic Ras signaling through directly binding to farnesylated Ras. It recruits farnesylated Ras to the non-lipid-raft membrane for interaction with downstream effectors. However, the cytosolic domain of NgBR itself is only partially folded.

Protein crystallization: Eluding the bottleneck of X-ray crystallography.

To date, X-ray crystallography remains the gold standard for the determination of macromolecular structure and protein substrate interactions. However, the unpredictability of obtaining a protein crystal remains the limiting factor and continues to be the bottleneck in determining protein structures. A vast amount of research has been conducted in order to circumvent this issue with limited success.

Structural basis of PDZ-mediated chemokine receptor CXCR2 scaffolding by guanine nucleotide exchange factor PDZ-RhoGEF.

The CXC chemokine receptor 2 (CXCR2) is a G protein coupled receptor mediating interleukin-8 chemotactic signaling and plays an important role in neutrophil mobility and tumor migration. However, efficient CXCR2 signaling requires PDZ domain-mediated scaffolding of signaling complexes at the plasma membrane and functional coupling of the signaling to specific downstream signaling pathways, in which only one PDZ protein has been characterized to interact with CXCR2. Here, we identified five novel CXCR2-binding PDZ-containing proteins, among which PDZ-RhoGEF is of particular interest because this PDZ and RGS-containing guanine nucleotide exchange factor (GEF) is also involved in cell signaling and mobility.

New open conformation of SMYD3 implicates conformational selection and allostery.

SMYD3 plays a key role in cancer cell viability, adhesion, migration and invasion. SMYD3 promotes formation of inducible regulatory T cells and is involved in reducing autoimmunity. However, the nearly "closed" substrate-binding site and poor in vitro H3K4 methyltransferase activity have obscured further understanding of this oncogenically related protein.

Molecular Dynamics Simulation Reveals Correlated Inter-Lobe Motion in Protein Lysine Methyltransferase SMYD2.

SMYD proteins are an exciting field of study as they are linked to many types of cancer-related pathways. Cardiac and skeletal muscle development and function also depend on SMYD proteins opening a possible avenue for cardiac-related treatment. Previous crystal structure studies have revealed that this special class of protein lysine methyltransferases have a bilobal structure, and an open-closed motion may regulate substrate specificity.

Purification of Histone Lysine Methyltransferase SMYD2 and Co-Crystallization with a Target Peptide from Estrogen Receptor α.

Methylation of estrogen receptor α by the histone lysine methyltransferase SMYD2 regulates ERα chromatin recruitment and its target gene expression. This protocol describes SMYD2 purification and crystallization of SMYD2 in complex with an ERα peptide. Recombinant SMYD2 is overexpressed in Escherichia coli cells.

Structure and function of SET and MYND domain-containing proteins.

SET (Suppressor of variegation, Enhancer of Zeste, Trithorax) and MYND (Myeloid-Nervy-DEAF1) domain-containing proteins (SMYD) have been found to methylate a variety of histone and non-histone targets which contribute to their various roles in cell regulation including chromatin remodeling, transcription, signal transduction, and cell cycle control. During early development, SMYD proteins are believed to act as an epigenetic regulator for myogenesis and cardiomyocyte differentiation as they are abundantly expressed in cardiac and skeletal muscle. SMYD proteins are also of therapeutic interest due to the growing list of carcinomas and cardiovascular diseases linked to SMYD overexpression or dysfunction making them a putative target for drug intervention.

PDZ Structure and Implication in Selective Drug Design against Cystic Fibrosis.

PDZ domains play an essential role in a number of cellular processes by facilitating protein scaffolding and assembly of protein complexes. These domains consist of 80 to 90 amino acids and are found to recognize short C-terminal sequences of target proteins. Protein complex formation between PDZ target molecules can lead to a number of signaling and regulatory cascades that may either promote or inhibit the activation of certain proteins.

Targeting the Root Cause of Cystic Fibrosis.

Cystic Fibrosis (CF) is a serious genetic condition caused by CF transmembrane conductance regulator (CFTR) mutation. CF patients have shortened lifespan due to airway obstruction, infection, and end-stage lung failure. However, recent development in CF therapy suggests a brighter future for CF patients.