Characterization of recombinant malarial RecQ DNA helicase

Suntornthiticharoen, Pattra; Srila, Witsanu; Chavalitshewinkoon-Petmitr, Porntip; Limudomporn, Paviga; Yamabhai, Montarop

doi:10.1016/j.molbiopara.2014.07.013

Cited by 7 publications

(10 citation statements)

References 15 publications

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“…Plasmodium has two representatives of the ‘canonical’ RecQ class of G4 DNA helicases, which have been designated Pf BLM and Pf WRN in previously-published in silico characterization (Additional file 9: Figure S3, [17, 43–45]). RecQs are 3’–5’ helicases homologous to the bacterial RecQ, with five representatives found in humans: BLM, WRN, RECQ1, RECQ4 and RECQ5 [46].…”

Section: Resultsmentioning

confidence: 99%

Recombination events among virulence genes in malaria parasites are associated with G-quadruplex-forming DNA motifs

et al. 2016

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BackgroundMalaria parasites of the genus Plasmodium possess large hyper-variable families of antigen-encoding genes. These are often variantly-expressed and are major virulence factors for immune evasion and the maintenance of chronic infections. Recombination and diversification of these gene families occurs readily, and may be promoted by G-quadruplex (G4) DNA motifs within and close to the variant genes. G4s have been shown to cause replication fork stalling, DNA breakage and recombination in model systems, but these motifs remain largely unstudied in Plasmodium.ResultsWe examined the nature and distribution of putative G4-forming sequences in multiple Plasmodium genomes, finding that their co-distribution with variant gene families is conserved across different Plasmodium species that have different types of variant gene families. In P. falciparum, where a large set of recombination events that occurred over time in cultured parasites has been mapped, we found a strong spatial association between these recombination events and putative G4-forming sequences. Finally, we searched Plasmodium genomes for the three classes of helicase that can unwind G4s: Plasmodium spp. have no identifiable homologue of the highly efficient G4 helicase PIF1, but they do encode two putative RecQ helicases and one homologue of the RAD3-family helicase FANCJ.ConclusionsOur analyses, conducted at the whole-genome level in multiple species of Plasmodium, support the concept that G4s are likely to be involved in recombination and diversification of antigen-encoding gene families in this important protozoan pathogen.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3183-3) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Recombination events among virulence genes in malaria parasites are associated with G-quadruplex-forming DNA motifs

et al. 2016

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“…Additionally, the two RecQ helicases may preferentially target particular substrates, such as regressed replication forks, recombination intermediates, telomeric G4s or R-loops: such a ‘division of labour’ occurs amongst the five-member RecQ family in mammals [ 19 ], and all these roles must presumably be condensed into a two-member family in Plasmodium . Recombinant protein fragments of both Pf BLM and Pf WRN have been shown to unwind partial-duplex DNA structures [ 21 , 40 ] but their affinity for other substrates has not been determined and the two helicases are certainly not functionally interchangeable.…”

Section: Discussionmentioning

confidence: 99%

“…In P . falciparum the effect upon telomeres appears to be exerted primarily by Pf BLM, but it is important to note that the two Plasmodium helicases are not necessarily functional homologs of their mammalian namesakes [ 21 ].…”

Section: Discussionmentioning

confidence: 99%

“…We therefore investigated whether either recombination or transcription in the P . falciparum genome could be affected by the two putative RecQ helicases encoded by this parasite, Pf WRN and Pf BLM [ 8 , 9 , 21 , 22 ]. Characterisation of RecQ mutant lines revealed that these helicases have widespread and profound effects on genome recombination and diversification of the virulence gene repertoire, as well as on transcription of large cohorts of genes.…”

Section: Introductionmentioning

confidence: 99%

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RecQ helicases in the malaria parasite Plasmodium falciparum affect genome stability, gene expression patterns and DNA replication dynamics

et al. 2018

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The malaria parasite Plasmodium falciparum has evolved an unusual genome structure. The majority of the genome is relatively stable, with mutation rates similar to most eukaryotic species. However, some regions are very unstable with high recombination rates, driving the generation of new immune evasion-associated var genes. The molecular factors controlling the inconsistent stability of this genome are not known. Here we studied the roles of the two putative RecQ helicases in P. falciparum, PfBLM and PfWRN. When PfWRN was knocked down, recombination rates increased four-fold, generating chromosomal abnormalities, a high rate of chimeric var genes and many microindels, particularly in known ‘fragile sites’. This is the first identification of a gene involved in suppressing recombination and maintaining genome stability in Plasmodium. By contrast, no change in mutation rate appeared when the second RecQ helicase, PfBLM, was mutated. At the transcriptional level, however, both helicases evidently modulate the transcription of large cohorts of genes, with several hundred genes—including a large proportion of vars—showing deregulated expression in each RecQ mutant. Aberrant processing of stalled replication forks is a possible mechanism underlying elevated mutation rates and this was assessed by measuring DNA replication dynamics in the RecQ mutant lines. Replication forks moved slowly and stalled at elevated rates in both mutants, confirming that RecQ helicases are required for efficient DNA replication. Overall, this work identifies the Plasmodium RecQ helicases as major players in DNA replication, antigenic diversification and genome stability in the most lethal human malaria parasite, with important implications for genome evolution in this pathogen.

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“…The characterization of RecQ family member PfBlm suggests that it is homologous and structurally similar to human HsBlm . The characterization of RecQ1 from multidrug‐resistant P. falciparum K1 strain has shown that PfRecQ1 contains ATP‐dependent 3′ to 5′ direction DNA helicase activity . PfRecQ1 was incapable of unwinding blunt‐end duplex DNA substrate and doxorubicin and daunorubicin inhibited its unwinding activity .…”

Section: Recq Family Of Plasmodium Falciparummentioning

confidence: 99%

Unraveling the importance of the malaria parasite helicases

Tuteja

2017

The FEBS Journal

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Malaria is a human parasitic disease caused by infection from Plasmodium species, particularly Plasmodium falciparum. Each year millions of people are infected with malaria and large numbers of deaths result due to this deadly infection. P. falciparum contains 14 chromosomes, nearly 5400 genes and a multistage life cycle in humans and mosquitoes. The control of malaria is still a challenge as the parasite is continuously developing resistance to available antimalarial drugs and the mosquito vector is developing resistance to insecticides. The availability of P. falciparum genome has resulted in the identification of parasite‐specific proteins that can be targeted without harmful effects to the human host. Toward this goal, we have been working on the identification and characterization of helicases in order to find parasite‐specific helicases, which can be used as novel drug targets to tackle the rising problem of drug resistance. Helicases are ATP‐dependent nucleic acid unwinding enzymes. The P. falciparum genome analysis depicts that it contains some parasite‐specific helicases and homologs to most of the human helicases. Here, we present an overview of P. falciparum helicases and their importance in parasite growth and survival.

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Characterization of recombinant malarial RecQ DNA helicase

Cited by 7 publications

References 15 publications

Recombination events among virulence genes in malaria parasites are associated with G-quadruplex-forming DNA motifs

Recombination events among virulence genes in malaria parasites are associated with G-quadruplex-forming DNA motifs

RecQ helicases in the malaria parasite Plasmodium falciparum affect genome stability, gene expression patterns and DNA replication dynamics

Unraveling the importance of the malaria parasite helicases

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