Disease relevance of POLL

• Over-expression of human DNA polymerase lambda in E. coli and characterization of the recombinant enzyme [1].
• We report here that the overexpression of human DNA polymerase kappa, an error-prone enzyme that is up-regulated in lung cancers, induces DNA breaks and stimulates DNA exchanges as well as aneuploidy [2].
• A shared V beta 13.1 DJ sequence of the CDR3 region, ND beta N, was demonstrated in 49 of 66 V beta 13.1+ clones (74.2%) from the glioma TIL, whereas only 4 of 33 clones (12.1%) were observed in the V beta 13.1+ clones from the PBL (p < 0.001) [3].
• Further evidence is given of by time rifampicin induction of beta-glucuronidase and beta-N acetylglucosaminidase and its possible relation to hepatitis and pancreatitis [4].

High impact information on POLL

• These observations have implications for the catalytic mechanism and putative DNA repair functions of Pol lambda [5].
• Pol lambda makes limited contacts with the template strand at the polymerase active site, and superimposition with Pol beta in a ternary complex suggests a shift in the position of the DNA at the active site that is reminiscent of a deletion intermediate [5].
• Here, we present a 2.1 A crystal structure of the catalytic core of Pol lambda in complex with DNA containing a two nucleotide gap [5].
• At low pH, protonation of the beta N terminus and His 147(HC3)beta within these clusters is postulated to destabilize the R-state and promote the acid-triggered, allosteric R-->T switch with concomitant O2 release [6].
• DNA polymerase lambda, a recently identified X-family homolog of DNA polymerase beta, is hypothesized to be a second polymerase involved in base-excision repair [7].

Biological context of POLL

• On the basis of its biochemical properties, Pol lambda has been implicated in various DNA repair pathways, such as abasic site translesion DNA synthesis, base excision repair and non-homologous end joining of double strand breaks [8].
• Human replication protein A can suppress the intrinsic in vitro mutator phenotype of human DNA polymerase lambda [9].
• Finally, Pol lambda is also phosphorylated in vivo in human cells and this phosphorylation is modulated during the cell cycle [8].
• The strong preference observed for pyrimidine versus purine nucleotide incorporation was found to be due, at least partially, to a steric block imposed by the residue Tyr-505 in the active site of pol lambda [10].
• Since the amino acid sequence for Pol lambda shares a high degree of homology to Pol beta, Pol lambda is considered to have a similar enzymatic nature to Pol beta [1].

Anatomical context of POLL

• BACKGROUND: DNA polymerase lambda (Pol lambda) was recently identified as a new member of the family X of DNA polymerases in eukaryotic cells [1].
• A fusion construct comprising Pol beta2 and green fluorescent protein exhibited a predominantly nuclear localization in transfected HeLa cells [11].
• The Pol beta2 gene is expressed in a tissue-specific manner, with transcripts being most abundant in testis [11].
• DNA polymerase lambda from calf thymus preferentially replicates damaged DNA [12].
• Shared amino acid sequences in the ND beta N and N alpha regions of the T cell receptors of tumor-infiltrating lymphocytes within malignant glioma [3].

Associations of POLL with chemical compounds

• This interaction stabilizes the binding of pol lambda to the primer template, thus increasing its affinity for the hydroxyl primer and its processivity in DNA synthesis [13].
• However, when tested on a template containing a bulky DNA lesion, such as the major cisplatin Pt-d(GpG) adduct, PCNA could not allow translesion synthesis by pol lambda [13].
• By constructing the truncated Pol lambda, the proline rich region was shown to act in a suppression of its polymerization activity [1].
• 0. Pol lambda was insensitive to aphidicolin, but was sensitive to dideoxynucleoside triphosphates or N-ethylmaleimide [1].
• The dRP lyase activity of Pol lambda, in coordination with its polymerization activity, efficiently repaired uracil-containing DNA in an in vitro reconstituted BER reaction [14].

Physical interactions of POLL

• Human DNA polymerase lambda functionally and physically interacts with proliferating cell nuclear antigen in normal and translesion DNA synthesis [13].
• In this paper, we show that hREV1 interacts with hpol eta as well as with hpol kappa and poorly with hpol iota [15].

Enzymatic interactions of POLL

• Here we demonstrate that purified pol lambda can efficiently catalyze gap-filling synthesis on DNA substrates mimicking NHEJ [16].
• Here, we present a kinetic and thermodynamic analysis of the DNA polymerase reaction catalyzed by full length human DNA pol lambda, showing that Mn(2+) favors specifically the catalytic step of nucleotide incorporation [17].

Regulatory relationships of POLL

• PCNA was found to stimulate efficient synthesis by pol lambda across an abasic (AP) site [13].
• APE1 has no influence on the strand displacement activity of Pol lambda though it stimulates strand displacement synthesis catalyzed with Pol beta [18].

Other interactions of POLL

• In this work, we searched by affinity chromatography for novel partners and we identified the cyclin-dependent kinase Cdk2 as novel partner of Pol lambda [8].
• FEN1 processes nicked DNA, thus removing a barrier to Pol lambda DNA synthesis [18].
• Finally, we show that the tumor suppressor protein p21(WAF1/CIP1) can efficiently compete in vitro with pol lambda for binding to PCNA [19].
• While DNA polymerase beta preferentially incorporated dCTP over dATP, DNA polymerase lambda did not modulate a preference for either dCTP or dATP when opposite 8-oxodG in single-nucleotide gapped DNA, as incorporation proceeded with essentially equal efficiency and probability [20].
• RESULTS: Recombinant human Pol lambda was shown to possess template-directed DNA polymerase activity in its monomeric form [1].

Analytical, diagnostic and therapeutic context of POLL

• In a few cases for which there is a nonconservative substitution in the sequence alignment, a structural comparison shows a positionally and, hence, probably a functionally equivalent residue, e.g., K60 in pol beta and K307 in pol lambda [21].
• Surface plasmon resonance analysis demonstrated that compound 5 bound selectively to the C-terminal 31kDa domain of pol beta and pol lambda containing a pol beta-like region [22].
• Immunoprecipitation from extracts of metabolically labeled transformed cells demonstrated that the truncated beta-subunit polypeptide (beta N) was neither transported to the plasma membrane nor assembled into an alpha-beta complex with the endogenous alpha-subunit [23].
• Cell fractionation experiments showed that the beta N truncated subunit remained unassembled within rough microsomes, suggesting that it never exited from the endoplasmic reticulum (ER) [23].

References