Gabriel Waksman

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Crystal structures of binary and ternary complexes of the E. coli Rep helicase bound to single-stranded (ss) DNA or ssDNA and ADP were determined to a resolution of 3.0 A and 3.2 A, respectively. The asymmetric unit in the crystals contains two Rep monomers differing from each other by a large reorientation of one of the domains, corresponding to a(More)
Type IV secretion systems are secretion nanomachines spanning the two membranes of Gram-negative bacteria. Three proteins, VirB7, VirB9 and VirB10, assemble into a 1.05 megadalton (MDa) core spanning the inner and outer membranes. This core consists of 14 copies of each of the proteins and forms two layers, the I and O layers, inserting in the inner and(More)
The crystal structures of two ternary complexes of the large fragment of Thermus aquaticus DNA polymerase I (Klentaq1) with a primer/template DNA and dideoxycytidine triphosphate, and that of a binary complex of the same enzyme with a primer/template DNA, were determined to a resolution of 2.3, 2.3 and 2.5 A, respectively. One ternary complex structure(More)
The structure of the homotetrameric DNA binding domain of the single stranded DNA binding protein from Escherichia coli (Eco SSB) bound to two 35-mer single stranded DNAs was determined to a resolution of 2.8 A. This structure describes the vast network of interactions that results in the extensive wrapping of single stranded DNA around the SSB tetramer and(More)
Many Gram-negative pathogens assemble architecturally and functionally diverse adhesive pili on their surfaces by the chaperone-usher pathway. Immunoglobulin-like periplasmic chaperones escort pilus subunits to the usher, a large protein complex that facilitates the translocation and assembly of subunits across the outer membrane. The crystal structure of(More)
The crystal structure of the Src SH2 domain complexed with a high affinity 11-residue phosphopeptide has been determined at 2.7 A resolution by X-ray diffraction. The peptide binds in an extended conformation and makes primary interactions with the SH2 domain at six central residues: PQ(pY)EEI. The phosphotyrosine and the isoleucine are tightly bound by two(More)
Periplasmic chaperones direct the assembly of adhesive, multi-subunit pilus fibers that play critical roles in bacterial pathogenesis. Pilus assembly occurs via a donor strand exchange mechanism in which the N-terminal extension of one subunit replaces the chaperone G(1) strand that transiently occupies a groove in the neighboring subunit. Here, we show(More)
The protein transduction domain (PTD) embedded in the HIV TAT protein (amino acids 47-57) has been shown to successfully mediate the introduction of heterologous peptides and proteins in excess of Mr 100,000 into mammalian cells in vitro and in vivo. We report here that the modeled structure of the TAT PTD is a strong amphipathic helix. On the basis of this(More)
Type IV secretion systems (T4SSs) are versatile secretion systems that are found in both Gram-negative and Gram-positive bacteria and secrete a wide range of substrates, from single proteins to protein-protein and protein-DNA complexes. They usually consist of 12 components that are organized into ATP-powered, double-membrane-spanning complexes. The(More)
Type IV secretion systems (T4SSs) are important virulence factors used by Gram-negative bacterial pathogens to inject effectors into host cells or to spread plasmids harboring antibiotic resistance genes. We report the 15 angstrom resolution cryo-electron microscopy structure of the core complex of a T4SS. The core complex is composed of three proteins,(More)