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A gene cluster encoding five enzymes of the mevalonate pathway had been cloned from Streptomyces sp. strain CL190. This gene cluster contained an additional ORF, orfD , encoding an unknown protein that was detected in some archaebacteria and some Gram-positive bacteria including Staphylococcus aureus . The recombinant product of orfD was purified as a soluble protein and characterized. The molecular mass of the enzyme was estimated to be 37 kDa by SDS-polyacrylamide gel electrophoresis and 155 kDa by gel filtration chromatography, suggesting that the enzyme is most likely to be a tetramer. The purified enzyme contained flavin mononucleotide (FMN) with the amount per tetramer being 1.4 to 1.6 mol/mol. The enzyme catalyzed the isomerization of isopentenyl diphosphate (IPP) to produce dimethylallyl diphosphate (DMAPP) in the presence of both FMN and NADPH. The Escherichia coli plasmid expressing orfD could complement the disrupted IPP isomerase gene in E. coli . These results indicate that orfD encodes an unusual IPP isomerase showing no sequence similarity to those of IPP isomerases identified to date. Based on the difference in enzymatic properties, we classify the IPP isomerases into two types: Type 2 for FMN- and NAD(P)H-dependent enzymes, and type 1 for the others. In view of the critical role of this isomerase in S. aureus and of the different enzymatic properties of mammalian (type 1) and S. aureus (type 2) isomerases, this unusual enzyme is considered to be a suitable molecular target for the screening of antibacterial drugs specific to S. aureus .

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In order to investigate the presence and prevalence of Lyme borreliosis (Lyme disease) Borrelia species, 312 unfed ticks were collected by flagging at a woodland area in Trakya, in the European side of Turkey, in May 2002. Twelve of 299 Ixodes ricinus ticks were infected with Borrelia spp., as determined by cultivation in BSK medium (prevalence rate 4·0 %). Ten pure cultures were subjected to further characterization by sequencing analysis of the 5S-23S rDNA intergenic spacer, 16S rDNA and flagellin gene. One isolate of Borrelia burgdorferi sensu stricto, two of Borrelia garinii (Eurasian type), two of Borrelia afzelii, four of Borrelia lusitaniae and one of Borrelia valaisiana were identified. However, no Asian-type B. garinii was found. Interestingly, all Borrelia species that are known to be carried by I. ricinus were discovered among the 10 isolates. These results provide the first evidence for the existence of the Lyme borreliosis agent in Turkey. INTRODUCTIONLyme borreliosis is the most prevalent tick-borne zoonosis in Europe, North America and the Far East (Burgdorfer et al., 1982;Gern et al., 1998;Steere, 2001;Yanagihara & Masuzawa, 1997). Borrelia burgdorferi (Johnson et al., 1984) sensu lato is classified into 11 species (Masuzawa et al., 2001). In Europe, Ixodes ricinus is the prominent vector tick and transmits five species, B. burgdorferi sensu stricto, Borrelia garinii (Baranton et al., 1992), Borrelia afzelii (Canica et al., 1993), Borrelia lusitaniae (Le Fleche et al., 1997) and Borrelia valaisiana (Wang et al., 1997). Of these five species, B. burgdorferi, B. afzelii and B. garinii are pathogenic to humans. On the other hand, the pathogenicity of B. lusitaniae and B. valaisiana remains to be elucidated (Escudero et al., 2000;Wang et al., 1999). B. burgdorferi has been isolated and identified in Europe from the vector tick, I. ricinus, wild mammals and patients, in contrast to Turkey, a country that constitutes a bridge between Europe and Asia. Based on RFLP analysis of the 5S-23S rRNA gene spacer, B. garinii were further classified into two subtypes, Eurasian type and Asian type. Eurasian-type B. garinii is found in both Europe and Asia; on the other hand, the Asian type is distributed only in east-Asian countries. Ixodes persulcatus is the vector of the Lyme disease borreliae B. garinii (Eurasian and Asian types) and B. afzelii in Asian countries such as Japan (Masuzawa et al., 1991(Masuzawa et al., , 1996a, far-eastern Russia (Masuzawa et al., 1997;Postic et al., 1997;Sato et al., 1996), north-eastern China (Li et al., 1998;Takada et al., 1998), western China (Uighur; Takada et al., 2001b) and Korea (T. Masuzawa, K. H. Park and M. K. Cho, unpublished). Borrelia strains genetically related to B. valaisiana found in Europe are distributed in the southern part of Asia, on Okinawa island, the southernmost islands of Japan (Takada et al., 2001a), Taiwan (Masuzawa et al., 2000), the southern part of China (Masuzawa et al., 2001) and Korea (Masuzawa et al., 1999).The aims of this study were to is...

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Previously, a novel, fast-growing spirochaete was isolated from the hard tick Hyalomma aegyptium, which infests tortoises (Testudo graeca), by using Barbour-Stoenner-Kelly (BSK) II medium; the tick samples were taken from the Istanbul area in northwestern Turkey [Gü ner et al. (2003). Microbiology 149, 2539Microbiology 149, -2544. Here is presented a detailed characterization of the spirochaete. Electron microscopy revealed that strain IST7T is morphologically similar to other spirochaetes of the genus Borrelia and possesses 15 to 16 flagellae that emerge from both polar regions. PFGE analysis revealed the genome to comprise a linear chromosome of approximately 1 Mb; two large linear plasmids of approximately 145 and 140 kb, and several small plasmids ranging from 50 to 20 kb in size were also found. The 16S rRNA gene sequence of this Borrelia isolate exhibited 99?4 to 99?8 % identity with other strains isolated from H. aegyptium and less than 99 % similarity with those of other Borrelia species. A phylogenetic tree, generated from 16S rRNA gene sequences, demonstrated that the spirochaete isolates from H. aegyptium clustered together and branched off from both Lyme-disease-related and relapsing-fever-associated Borrelia species. A single copy of the rrs gene was detected in the genome of strain IST7 T by Southern hybridization. DNA-DNA hybridization results showed that strain IST7 T was distinct from Lyme-disease-related Borrelia, Borrelia burgdorferi and the relapsing-fever-associated species Borrelia hermsii. The G+C content of strain IST7 T is 30?0 mol%. From these genetic features, a novel Borrelia species, Borrelia turcica sp. nov., is proposed; the type strain is IST7 T (=JCM 11958 T =DSM 16138 T ).