IS200 is not a member of the IS600 family of insertion sequences

Nucleic Acids Resea ch, Vol. 19, No. 6 1343 IS200 is no a membe o he 1S600 amily o inse ion sequences Isid e Gibe , Ka en Ca oll1, Da id R.Hillya d', Jo di Ba be and Josep Casadesus2* Depa amen de Gene ica i Mic obiologia, Uni e si a Au onoma de Ba celona, 08193 Bella e a, Ba celona, Spain, 'Depa men o Pa hology, Uni e si y o U ah, Sal Lake Ci y, UT 84112, USA and 2Depa amen o de Gen6 ica, Uni e sidad de Se illa, Apa ado 1095, 41080 Se ille, Spain Submi ed Janua y 2, 1991 EMBL accession no. X56834 IS200 is an inse ion sequence p esen in all Salmonella species excep S. agona (1, 2). The elemen is absen om all o he En e obac e iaceae, wi h he excep ion o some s ains o Shigella lexne i and Shigella sonnei (2). I had been hypo hesized ha he i s mu a ion cha ac e ized as an IS200 inse ion, hisD984: :IS200 (1, 3) migh ac ually be a dele ion mu an o he Shigella inse ion elemen IS630 (4). Howe e , sequencing o he ends o a second mu a ion caused by IS200 inse ion la e sugges ed ha IS200 was a dis inc inse ion elemen (5). We ecen ly ob ained he comple e nucleo ide sequence o he inse ion elemen IS200 inse ed in he his idine ope on o S. yphimu iwn (causing he mu a ion hisD984: :IS200). The elemen is 708 bp long; i his size co esponds o a wild- ype elemen , IS200 can be conside ed he smalles inse ion sequence known (6). A diag am o he hypo he ical s uc u e o IS200 is p esen ed in Figu e 1. Unlike many inse ion elemen s, IS200 lacks enninal in e ed epea s, as p e iously epo ed (3, 5). The elemen con ains h ee po en ial open eading ames (ORF 1, ORF 2 and ORF 3), whose coding capabili ies a e 69, 71 and 58 amino acids, espec i ely. ORF2 and ORF3 a e o e lapping; he exis ence o o e lapping ORFs is no su p ising, since i seems o be ex emely common among bac e ial inse ion sequences (6). O he in e es ing ea u es o IS200 a e he ollowing: (i) Th ee po en ial hai pin loops a e loca ed nea he ' igh ' end o he elemen (Figu e 1). One o he loops, cen e ed on base 688, s ongly eminds o a Rho-independen ansc ip ion e mina o , as p e iously sugges ed (3). Two smalle hai pins a e cen e ed on bases 608 and 665. (ii) Two nea ly pe ec in e ed epea s o 20 bp exis wi hin he sequence. Bo h epea s a e loca ed nea he ' igh ' end, ex ending be ween nucleo ides 565-584 and 629-648 (Figu e 1). The epea s di e by only 4 misma ches and hei po en ial biological signi icance is unknown. A sea ch in he EMBL da a bank has con i med ha IS200 is no a dele ion mu an o IS630, al hough wo disc e e egions o homology (8 and 10 bp long) appea o exis be ween IS200 and IS630. Likewise, wo sho egions o homology (7 and 8 bp long) a e ound be ween IS200 and he Shigella sonnei inse ion sequence IS640. Two DNA s e ches, 10 and 11 bp long, homologous o he S. sonnei elemen IS600 ha e also been ound. P obes lacking homology wi h he Shigella elemen s IS600, IS630 and IS640 can now be ob ained by cloning speci ic, in e nal agmen s o IS200. These p obes a e expec ed o be use ul o ind ou whe he he hybndiza ion ound be ween IS200 p obes and ce ain Shigella DNAs (2) was caused o no by c oss- hyb idiza ion be ween IS200 and Shigella inse ion elemen s. ACKNOWLEDGMENTS The S. yphimu ium s ain ca ying he mu a ion hisD984: :IS200 was kindly p o ided by John R.Ro h. We a e g a e ul o And 6s Ga z6n o in e es ing discussions and o Ma en Ma sh o help ul assis ance. REFERENCES 1. Lam,S. and Ro h,J.R. (1983) Cell 34, 951-960. 2. Gibe ,I., Ba be,J. and Casadesds,J. (1990) J. Gen. Mic obiol. 136, 2555-2560. 3. Lam,S. and Ro h,J.R. (1986) J. Mol. Biol. 187, 157-167. 4. Ma su ani,S., O hsubo,H., Maeda,Y. and O hsubo,E. (1987). J. MoI. Bio. 196, 445-455. 5. O'Reilly,C., Black,G.W., La ey,R. and McConnell,D.J. (1990). J. Bac e iol. 172, 6599-6601. 6. Galas,D.J. and Chandle ,M. (1989). In Be g,D.M. and Howe,M.M. (eds) Mobile DNA. Ame ican Socie y o Mic obiology, pp. 109-162. EI SIDE 1 920 SIDE ORF2 ORF1 75 290 384 593 ORF 3 75 251 Figu e 1. A diag am o he inse ion hisD984::IS200. The o ien a ion o he inse ion elemen in he hisD gene is indica ed by he 'O' and 'E' sides. Po en ial ORFs, hai pin loops and in e nal in e ed epea s a e also shown. The ela i e sizes o he hai pins is indica ed (bu no d awn o scale). * To whom co espondence should be add essed .:) 1991 Ox o d Uni e si y P ess