Dimeric proteins bacteriophage

Figure 16.20 The structure of the complex between a dimer of the coat protein of bacteriophage MS2 and the RNA fragment shown in Figure 16.19. One subunit of the coat protein dimer is green, the other is violet and the RNA fragment is orange. Bases that form sequence specific interactions with the protein are red. (Adapted from a diagram provided by L. Liijas.)...

RuvC is an endonuclease that is highly specific for Holliday junctions. It is a resolvase that cuts at either points a,a or b,b of Eq. 27-11 to form either "patched" or "spliced" recombinant DNA (Fig. 27-26C). Similar resolvases process bacteriophage DNA562-564 and have also been found in yeasts and in mammals.565 566 All are dimeric metal ion-dependent proteins.567... 

Often, DNA-binding proteins must associate to become active. For example, CD was used to study the concentration-dependent unfolding of bacteriophage P22 Arc repressor, which is associated with a monomer-dimer equilibrium [191], One major class of DNA-... 

Wickner and colleagues have demonstrated a role for the E. coli dnaK protein in replication of bacteriophage PI (Wickner, 1990). In PI replication, the phage repA protein binds specifically to the PI origin of replication it appears to be a monomeric repA that binds to the origin with high affinity. Dimers of repA, in a 2 2 subunit complex with the E. coli... 

In addition, three enzymes involved in DNA replication, including DNA primases, prokaryotic DNA topoisomerase I and some hexameric DNA helicases, are also classic zinc-ribbon proteins. In bacteriophage DNA primases, mutations of the zinc-binding residues abrogate the synthesis of RNA primers for lagging strand DNA synthesis. Strikingly, each subunit of the mini-chromosomal maintenance (MCM) protein, a heterohexameric helicase that initiates DNA replication in S. cerevisiae, contains an independently folded zinc-ribbon domain that appears to stabilize the dodecameric structure (a dimer of hexamers) of this replication complex. ... 

Figure 3.48. Quaternary Structure. The Cro protein of bacteriophage A, is a dimer of identical subunits.

Wu Y, Shih SC, Goto NK (2007) Probing the structure of the Ff bacteriophage major coat protein transmembrane helix dimer by solution NMR. Biochim Biophys Acta 1768 3206-3215... 

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