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Evidence for a defective prophage on the chromosome of Methanobacterium wolfei
R Stettler1, C Thurner, D Stax
1Mikrobiologisches Institut, Eidgenössische Technische Hochschule, ETH-Zentrum, Zürich, Switzerland.
Abstract:
Evidence shows the presence on the chromosome of Methanobacterium wolfei of a defective prophage which, by DNA-DNA hybridization, is closely related to the virulent archaeophage psi M1 of Methanobacterium thermoautotrophicum Marburg. Partial sequencing of a M. wolfei 16S rRNA gene and phylogenetic analysis indicated that this organism is more closely related to other representatives of the genus Methanobacterium than to M. thermoautotrophicum Marburg. The chromosomal region of M. wolfei encoding the putative prophage was found to be deleted for two non-contiguous segments of the phage psi M1 genome and thus encompassed only 80 to 90% of the psi M1 DNA. The prophage region was mapped to a 30 kb restriction fragment on the physical map of the M. wolfei chromosome. A randomly chosen DNA fragment was cloned from phage psi M1 DNA, as was its homologous counterpart from the chromosome of M. wolfei. The 126-bp region present in both clones exhibited 100% sequence identity.
Insights
A defective prophage in Methanobacterium wolfei is closely related to archaeophage psi M1. Despite deletions, a conserved region shows 100% sequence identity, aiding in understanding archaeal virus-host interactions.
Area of Science:
- Microbiology
- Virology
- Genetics
Background:
- Methanobacterium wolfei harbors a defective prophage.
- This prophage shows close genetic relation to the virulent archaeophage psi M1.
Purpose of the Study:
- To investigate the genetic relationship between the M. wolfei prophage and archaeophage psi M1.
- To characterize the prophage's integration and sequence homology within the M. wolfei genome.
Main Methods:
- DNA-DNA hybridization was used to assess prophage relatedness.
- Partial 16S rRNA gene sequencing and phylogenetic analysis were performed.
- Prophage region mapping and DNA fragment cloning were conducted.
Main Results:
- The M. wolfei prophage is closely related to archaeophage psi M1.
- Phylogenetic analysis confirmed M. wolfei's distinctness from M. thermoautotrophicum Marburg.
- The prophage region in M. wolfei contains 80-90% of the psi M1 genome, with two deletions.
- A 126-bp conserved region between the prophage and psi M1 exhibited 100% sequence identity.
Conclusions:
- The defective prophage in M. wolfei represents a remnant of archaeophage psi M1 infection.
- The high sequence identity in a specific region suggests functional importance or recent shared ancestry.