Mesophilic cyanobacteria producing thermophilic restriction endonucleases

Abstract

When searching for the site-specific endonucleases in several strains of Phormidium we made the following observations. Among the 16 strains that originated from 15 species of Phormidium, 12 produced one or more restriction enzymes, of which two produced the highly thermophilic restriction endonucleases PtaI and PpaAII with their optimum activity at 65-80 degrees C, which is far above the lethal temperature for the host microorganism (40 degrees C). These two temperature-resistant enzymes are isoschizomers of known BspMII and TaqI endonucleases, respectively. The presence of the thermophilic TaqI isoschizomer does not seem to play any role in the mesophilic host microorganism, which does not even contain an active cognate methyltransferase. Among the remaining 10 strains, six produced isoschizomers of endonucleases which we first described in cyanobacteria, namely: PfaAII (NdeI), PinBII and PtaI (BspMII), PlaAII (RsalI), PpaAII, PpeI (ApaI). Two enzymes, PauAII (AhaIII) and PfaAII (NdeI), belong to a group of a very rarely occurring isoschizomers. Out of 21 cyanobacterial endonucleases investigated by us, four were active in a wide range of temperatures (from 15 to 60 degrees C) which also extended the optimal growth temperature of the hosts. We assume that our observation on the presence of temperature-resistant restriction enzymes in mesophilic hosts supports the idea of horizontal gene transfer. Restriction modification systems may be an excellent tool for investigation of that phenomenon.

Microdiversity shapes the traits, niche space, and biogeography of microbial taxa

“…In Mycobacterium tuberculosis and E. coli , mutations in the rpoB gene can confer resistance to the antibiotic rifampicin (Telenti et al ., ; Rodriguez‐Verdugo et al ., ; Hammerling et al ., ). Additionally, HGT may result in a change in growth optima along an already acquired trait axis (Piechula et al ., ). For example, a study of Bacillus subtilis isolated from soil communities showed that the addition of maltose genes by HGT to a specific sub‐taxa resulted in higher growth on that substrate when compared with other closely related sub‐taxa and, thus, Maestro rather than Renaissance trait differentiation.…”

Applications of cyanobacteria in biotechnology

“…2004). Piechula et al. (2001) demonstrated that some cyanobacteria can produce thermostable enzymes.…”

Identification of a DNA restriction-modification system in Pectobacterium carotovorum strains isolated from Poland

“…As was suggested by several authors (De Waard and Duyvesteyn 1980; Janulaitis et al. 1988; Piechula et al. 2001), presence or absence of restriction endonucleases might be helpful in distinguishing strains of the same species or subspecies.…”

“…After 24 h of incubation in 1.0 l Luria Broth at 25°C, cultures of P. carotovorum were harvested by centrifugation, washed in buffer (10 mmol l −1 Tris–HCl, 25 mmol l −1 KCl, pH 6·8), suspended in 3·0 ml sonication buffer (10 mmol l −1 Tris–HCl, 50 mmol l −1 KCl, pH 6·8) and kept frozen until the analysis for the presence of restriction endonucleases was performed. The restriction enzymes were isolated as described earlier (Piechula et al. 2001).…”

“…The occurrence of different R‐M systems in different subspecies can be an indicator confirming their genetic difference (Janulaitis et al. 1988; Piechula et al. 2001).…”