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Structural biology at NIH - structure-function studies; dna replication enzyme complexes

• Senior Investigator: Nancy g. Nossal

• Affiliation: laboratory of molecular and cellular biology, NIDDK

• Research: structure and function of multi-enzyme dna replication complexes.

• We have been studying the molecular mechanisms controlling dna replication using a multi-enzyme system of proteins encoded by bacteriophage t4. We have developed procedures for the purification of the polymerase, polymerase accessory proteins, dna binding protein, primase-helicase components, and RNaseH required for dna - synthesis in this system. We are currently collaborating with Craig hyde and Tim Mueser (laboratory of structural biology, NIAMS), who are trying to crystallize these proteins.

• Personnel/Resources:

• Publications:

M.W. Frey, N.G. Nossal, T.L. Capson, & s.J. Benkovic (1993). Proc. Natl. Acad. Sci. USA 90:2579-2583. Construction and characterization of a bacteriophage t4 dna polymerase deficient in 3'->5' exonuclease activity.

H.C. Hollingsworth, & N.G. Nossal (1991). J. Biol. Chem. 266:1888-1897. Bacteriophage t4 encodes an rNase H which removes primers made by the t4 dna replication system in vitro.

T.C. Capson, s. Benkovic, & N.G. Nossal (1991). Cell 65:249-258. Protein-dna cross-linking demonstrates stepwise ATP-dependent assembly of t4 dna polymerase and its accessory proteins on the primer-template.

N.G. Nossal (1992). FASEB j. 6:871-878. Protein-protein interactions at a dna replication fork: bacteriophage t4 as a model.

P. Spacciapoli, & N.G. Nossal (1993). J. Biol. Chem. (in press). A single mutation in bacteriophage t4 dna polymerase (A737V, tsL141) decreases its processivity as a polymerase and increases its processivity as a 3'->5' exonuclease.

P. Spacciapoli, & N.G. Nossal (1993). J. Biol. Chem. (in press). Interaction of dna polymerase and dna helicase within the bacteriophage t4 dna replication complex: leading strand synthesis by the t4 dna polymerase mutant A737V (tsL141) requires the t4 gene 59 helicase assembly protein.

• Contact: dr. N. Nossal, Bldg. 8, room 2A-19. NIDDK, NIH, Bethesda, md 20892.

Tel: (301) 496-2724 Fax: (301) 402-0240

Figure: model of bacteriophage t4 dna replication proteins at a replication fork.