\u3cem\u3eBorrelia burgdorferi\u3c/em\u3e EbfC Defines a Newly-Identified, Widespread Family of Bacterial DNA-Binding Proteins

The Lyme disease spirochete, Borrelia burgdorferi, encodes a novel type of DNA-binding protein named EbfC. Orthologs of EbfC are encoded by a wide range of bacterial species, so characterization of the borrelial protein has implications that span the eubacterial kingdom. The present work defines the DNA sequence required for high-affinity binding by EbfC to be the 4 bp broken palindrome GTnAC, where ‘n’ can be any nucleotide. Two high-affinity EbfC-binding sites are located immediately 5′ of B. burgdorferi erp transcriptional promoters, and binding of EbfC was found to alter the conformation of erp promoter DNA. Consensus EbfC-binding sites are abundantly distributed throughout the B. burgdorferi genome, occurring approximately once every 1 kb. These and other features of EbfC suggest that this small protein and its orthologs may represent a distinctive type of bacterial nucleoid-associated protein. EbfC was shown to bind DNA as a homodimer, and site-directed mutagenesis studies indicated that EbfC and its orthologs appear to bind DNA via a novel α-helical ‘tweezer’-like structure

Leptospira interrogans Endostatin-Like Outer Membrane Proteins Bind Host Fibronectin, Laminin and Regulators of Complement

The pathogenic spirochete Leptospira interrogans disseminates throughout its hosts via the bloodstream, then invades and colonizes a variety of host tissues. Infectious leptospires are resistant to killing by their hosts' alternative pathway of complement-mediated killing, and interact with various host extracellular matrix (ECM) components. The LenA outer surface protein (formerly called LfhA and Lsa24) was previously shown to bind the host ECM component laminin and the complement regulators factor H and factor H-related protein-1. We now demonstrate that infectious L. interrogans contain five additional paralogs of lenA, which we designated lenB, lenC, lenD, lenE and lenF. All six genes encode domains predicted to bear structural and functional similarities with mammalian endostatins. Sequence analyses of genes from seven infectious L. interrogans serovars indicated development of sequence diversity through recombination and intragenic duplication. LenB was found to bind human factor H, and all of the newly-described Len proteins bound laminin. In addition, LenB, LenC, LenD, LenE and LenF all exhibited affinities for fibronectin, a distinct host extracellular matrix protein. These characteristics suggest that Len proteins together facilitate invasion and colonization of host tissues, and protect against host immune responses during mammalian infection

The Influence of DX-52-1 and Phosphorylation on the Interactions of Galectin-3 with its Binding Partners

The Influence of DX-52-1 and Phosphorylation on the Interactions of Galectin-3 with its Binding Partners Matthew L. Rotondi, PhD University of Connecticut, 2015 Galectin-3, a member of a large family of animal based β-galactoside-binding lectins has been shown to play a role in a number of cellular and pathogenic processes. This protein has been shown throughout the literature to interact with a diverse multiplicity of proteins, involved in a diverse array of cellular functions, including cell migration and cell proliferation, both of which are of particular in regards to cancer research. Covalent modifications to Galectin-3 that can undermine its binding partner interactions would definitely prove useful in such an enterprise. DX-52-1, a semisynthetic an analog of the natural product quinocarcin, has been shown by the Fenteany Group, to demonstrate remarkable anti-migration and anti-proliferation properties with regard to a number of cancer cell lines. Furthermore this molecule has been shown to bind strongly and specifically to Galectin-3 and Radixin. In the course of this research DX-52-1 has been shown to modestly undermine a number of binding partner interactions of Galectin-3. It has also been demonstrated that the phosphorylation of Galectin-3 also influences its binding to DX-52-1. It has been further demonstrated that DX-52-1 may have an even more potent effect on the formation of higher order complexes that contain Galectin-3. This observation may serve to further explain the strong anti-migration and anti-proliferation effects of DX-52-1. In the course of this work, efforts to map the binding site of DX-52-1 on Galectin-3 were undertaken. In the course of those efforts a novel method to narrow down potential binding sites was developed. Furthermore structure activity relationship studies were performed to determine the importance of certain functional groups on the binding properties of DX-52-1 in regard to Galectin-3 and Radixin as wells as its anti-cellular properties. The results of these SAR studies show a link between the binding of DX-52-1 to Galectin-3 and its anti-migration and anti-proliferation properties