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Research has been conducted on DNA polymerase zeta. The results of genetic and biochemical analysis of yeast DNA polymerase zeta demonstrate that this polymerase is important for error-free replication past thymine glycol.

Research has been conducted on XPG gene which causes Cockayne syndrome onset. The evidence that Saccharomyces cerevisiae RAD2, an XPC gene counterpart, promotes RNA polymerase II transcription is presented.

Methylophaga aminisulfidivorans MPT is a marine methylotrophic bacterium that utilizes C1 compounds such as methanol as a carbon and energy source. The released electron from oxidation flows through a methanol-oxidizing system (MOX) consisting of a series of electron-transfer proteins encoded by the mox operon. One of the key enzymes in the pathway is methanol dehydrogenase (MDH), which contains the prosthetic group pyrroloquinoline quinone (PQQ) and converts methanol to formaldehyde in the periplasm by transferring two electrons from the oxidation of one methanol molecule to the electron acceptor cytochrome cL. In order to obtain molecular insights into the oxidation mechanism, a native heterotetrameric α2β2 MDH complex was directly purified from M. aminisulfidivorans MPT grown in the presence of methanol and crystallized. The crystal diffracted to 1.7 Å resolution and belonged to the monoclinic space group P21 (unit-cell parameters a = 63.9, b = 109.5, c = 95.6 Å, β = 100.5°). The asymmetric unit of the crystal contained one heterotetrameric complex, with a calculated Matthews coefficient of 2.24 Å3 Da−1 and a solvent content of 45.0%. [ABSTRACT FROM AUTHOR]

Methylophaga aminisulfidivorans MPT is a marine methylotrophic bacterium that utilizes C1 compounds such as methanol as a carbon and energy source. The released electron from oxidation flows through a methanol-oxidizing system (MOX) consisting of a series of electron-transfer proteins encoded by the mox operon. One of the key enzymes in the pathway is methanol dehydrogenase (MDH), which contains the prosthetic group pyrroloquinoline quinone (PQQ) and converts methanol to formaldehyde in the periplasm by transferring two electrons from the oxidation of one methanol molecule to the electron acceptor cytochrome cL. In order to obtain molecular insights into the oxidation mechanism, a native heterotetrameric α2β2 MDH complex was directly purified from M. aminisulfidivorans MPT grown in the presence of methanol and crystallized. The crystal diffracted to 1.7 Å resolution and belonged to the monoclinic space group P21 (unit-cell parameters a = 63.9, b = 109.5, c = 95.6 Å, β = 100.5°). The asymmetric unit of the crystal contained one heterotetrameric complex, with a calculated Matthews coefficient of 2.24 Å3 Da−1 and a solvent content of 45.0%. [ABSTRACT FROM AUTHOR]

Mutations in the human XPG gene cause Cockayne syndrome (CS) and xeroderma pigmentosum (XP). Transcription defects have been suggested as the fundamental cause of CS; however, defining CS as a transcription syndrome is inconclusive. In particular, the function of XPG in transcription has not been clearly demonstrated. Here, we provide evidence for the involvement of RAD2, the Saccharomyces cerevisiae counterpart of XPG, in cell cycle regulation and efficient actin assembly following ultraviolet irradiation. RAD2 C-terminal deletion, which resembles the XPG mutation found in XPG/CS cells, caused cell growth arrest, the cell cycle stalling, a defective α-factor response, shortened lifespan, cell polarity defect, and misregulated actin-dynamics after DNA damage. Overexpression of the C-terminal 65 amino acids of Rad2p was sufficient to induce hyper-cell polarization. In addition, RAD2 genetically interacts with TPM1 during cell polarization. These results provide insights into the role of RAD2 in post-UV irradiation cell cycle regulation and actin assembly, which may be an underlying cause of XPG/CS.

DNA polymerase zeta (Polzeta) promotes the mutagenic bypass of DNA lesions in eukaryotes. Genetic studies in Saccharomyces cerevisiae have indicated that relative to the contribution of other pathways, Polzeta makes only a modest contribution to lesion bypass. Intriguingly, however, disruption of the REV3 gene, which encodes the catalytic subunit of Polzeta, causes early embryonic lethality in mice. Here, we present genetic and biochemical evidence for the requirement of yeast Polzeta for predominantly error-free replication past thymine glycol (Tg), a DNA lesion formed frequently by free radical attack. These results raise the possibility that, as in yeast, in higher eukaryotes also, Polzeta makes a major contribution to the replicative bypass of Tgs as well as other lesions that block synthesis by replicative DNA polymerases. Such a preeminent role of Polzeta in lesion bypass would ensure that rapid cell divisions continue unabated during early embryonic development, thereby minimizing the generation of DNA strand breaks, chromosome aberrations, and the ensuing apoptotic response.