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Functional analysis of the superfamily 1 DNA helicases encoded by Mycoplasma pneumoniae and Mycoplasma genitalium.

ABSTRACT: The DNA recombination and repair machinery of Mycoplasma pneumoniae is composed of a limited set of approximately 11 proteins. Two of these proteins were predicted to be encoded by neighboring open reading frames (ORFs) MPN340 and MPN341. Both ORFs were found to have sequence similarity with genes that encode proteins belonging to the DNA helicase superfamily 1 (SF1). Interestingly, while a homolog of the MPN341 ORF is present in the genome of Mycoplasma genitalium (ORF MG244), MPN340 is an M. pneumoniae-specific ORF that is not found in other mycoplasmas. Moreover, the length of MPN340 (1590 base pairs [bp]) is considerably shorter than that of MPN341 (2148 bp). Examination of the MPN340-encoded amino acid sequence indicated that it may lack a so-called 2B subdomain, which is found in most SF1 DNA helicases. Also, the MPN340-encoded amino acid sequence was found to differ between subtype 1 strain M129 and subtype 2 strain FH at three amino acid positions. Both protein variants, which were termed PcrA(s) M129 and PcrA(s) FH, respectively, as well as the MPN341- and MG244-encoded proteins (PcrA Mpn and PcrA Mge , respectively), were purified, and tested for their ability to interact with DNA. While PcrA Mpn and PcrA Mge were found to bind preferentially to single-stranded DNA, both PcrA(s) M129 and PcrA(s) FH did not demonstrate significant DNA binding. However, all four proteins were found to have divalent cation- and ATP-dependent DNA helicase activity. The proteins displayed highest activity on partially double-stranded DNA substrates carrying 3' single-stranded extensions.

SUBMITTER: Estevao S

PROVIDER: S-EPMC3720892 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Functional analysis of the superfamily 1 DNA helicases encoded by Mycoplasma pneumoniae and Mycoplasma genitalium.

Estevão Silvia S van der Heul Helga U HU Sluijter Marcel M Hoogenboezem Theo T Hartwig Nico G NG van Rossum Annemarie M C AM Vink Cornelis C

PloS one 20130723 7

The DNA recombination and repair machinery of Mycoplasma pneumoniae is composed of a limited set of approximately 11 proteins. Two of these proteins were predicted to be encoded by neighboring open reading frames (ORFs) MPN340 and MPN341. Both ORFs were found to have sequence similarity with genes that encode proteins belonging to the DNA helicase superfamily 1 (SF1). Interestingly, while a homolog of the MPN341 ORF is present in the genome of Mycoplasma genitalium (ORF MG244), MPN340 is an M. p ...[more]

PMID: 23894687

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Project description:The discovery of small open reading frames (smORFs) encoding for polypeptides (SEPs; <100aa) highlights that the coding capacity of the genomes has been underestimated. Most ORF-finding algorithms have historically set a minimum threshold length of 100 aa. As consequence, some transcripts encoding for SEPs, were erroneously discarded or classified as non-coding RNAs (ncRNAs). With this experiments we try to experimentally assess the existence and complexity of these small proteins. The experimental design includes: After growing each Mycoplasma for 6h at 37°C, cells were washed twice with PBS and lysed with 700 µl of Qiazol buffer. Then, samples were lysed with 700 µl of Qiazol buffer. RNA extractions were performed by using the miRNeasy mini Kit (Qiagen) following the instructions of the manufacturer. Libraries for RNA-seq were prepared following directional RNA-seq library preparation and sequencing. Briefly, 1 µg of total RNA was fragmented to ~100-150 nt using NEB Next Magnesium RNA Fragmentation Module (ref. E6150S, NEB). Treatments with Antarctic phosphatase (ref. M0289S, NEB) and PNK (ref. M0201S, NEB) were performed in order to make the 5’ and 3’ ends of the RNA available for adapter ligation. Samples were further processed using the TruSeq small RNA Sample Prep Kit (ref. RS-200-0012, Illumina) according to the manufacturer's protocol. In summary, 3’ adapters and subsequently 5’ adapters were ligated to the RNA. cDNA was synthesized using reverse transcriptase (SuperScript II, ref. 18064-014, Invitrogen) and a specific primer (RNA RT Primer) complementary to the 3’ RNA adapter. cDNA was further amplified by PCR using indexed adapters supplied in the kit. Finally, size selection of the libraries was performed using 6% Novex® TBE Gels (ref. EC6265BOX, Life Technologies). Fragments with insert sizes of 100 to 130 bp were cut from the gel, and cDNA was precipitated and eluted in 10 µl of elution buffer. Double-stranded templates were cluster amplified and sequenced on an Illumina HiSeq 2000.

Dataset Information

Functional analysis of the superfamily 1 DNA helicases encoded by Mycoplasma pneumoniae and Mycoplasma genitalium.

Publications

Functional analysis of the superfamily 1 DNA helicases encoded by Mycoplasma pneumoniae and Mycoplasma genitalium.

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