title: A new algorithm for cluster analysis of genomic methylation: the Helicobacter pylori case.
abstract: BACKGROUND
  The genomic methylation analysis is useful to type bacteria that have a high number of expressed type II methyltransferases. Methyltransferases are usually committed to Restriction and Modification (R-M) systems, in which the restriction endonuclease imposes high pressure on the expression of the cognate methyltransferase that hinder R-M system loss. Conventional cluster methods do not reflect this tendency. An algorithm was developed for dendrogram construction reflecting the propensity for conservation of R-M Type II systems.
  
  
  RESULTS
  The new algorithm was applied to 52 Helicobacter pylori strains from different geographical regions and compared with conventional clustering methods. The algorithm works by first grouping strains that share a common minimum set of R-M systems and gradually adds strains according to the number of the R-M systems acquired. Dendrograms revealed a cluster of African strains, which suggest that R-M systems are present in H.pylori genome since its human host migrates from Africa.
  
  
  BACKGROUND
  The software files are available at http://www.ff.ul.pt/paginas/jvitor/Bioinformatics/MCRM_algorithm.zip.
authors: Engineering Faculty, Portuguese Catholic University, Estrada Octávio Pato, 2635-631 Rio de Mouro, Portugal. filipavale@fe.ucp.pt
authors: F F
authors: FF
authors: Vale
authors: P
authors: P
authors: Encarnação
authors: J M B
authors: JM
authors: Vítor
mesh_terms: D000465:Algorithms; D001483:Base Sequence; D002874:Chromosome Mapping / Q000379:methods*; D016000:Cluster Analysis; D019175:DNA Methylation; D015280:DNA Restriction-Modification Enzymes / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics*; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics*; D008969:Molecular Sequence Data
chemical_list: D015280:DNA Restriction-Modification Enzymes; D004269:DNA, Bacterial