Streptococcus pneumoniae, transformation

Francis KP, Yu J, Bellinger-Kawahara C, et al. Visualizing pneumococcal infections in the lungs of live mice using bioluminescent Streptococcus pneumoniae transformed with a novel Gram-positive lux transposon. Infect Iirnnun 2001 69 3350-8. 

Francis, K. P., Yu, J., BeUinger-Kawahara, C., Joh, D., Hawkinson, M. J., Xiao, G., Purchio, T. F., Caparon, M. G., Lipsitch, M., and Contag, P. R. (2001) Visualizing pneumococcal infections in the lungs of live mice using bioluminescent Streptococcus pneumoniae transformed with a novel gram-positive lux transposon. Infect. Immun. 69, 3350-3358. 

In contrast to macrolides, the targets of (3-lactams, the penicillin binding proteins (PBPs) require several mutations in order to become resistant while simultaneously maintaining their viable function as cell wall transpeptidases/transglycosidases. Thus, in order to achieve clinically relevant resistance Streptococcus pneumoniae uses a unique strategy to rapidly accumulate several point mutations. Due to its natural competence for transformation during respiratory tract... 

The type-specific capsular polysaccharide from Streptococcus pneumoniae type 5 contains 2-acetamido-2,6-dideoxy- -D-x>>/o-hexopyranosyl-4-ulose residues (17). Sugar nucleotides of hexos-4-uloses are important intermediates in the transformation of sugars during the biosynthesis, but this is the only known example of such a sugar as a polysaccharide component. 

Ola Johnsborg is a research scientist. He received his Ph.D. in 2003 from the Norwegian University of Life Sciences. His Ph.D. work was on molecular mechanisms underlying regulation of bacteriocin production in Laaobacillus plantarum. Since then he has been studying horizontal gene transfer by means of competence for natural transformation in the human pathogenic bacterium Streptococcus pneumoniae. 

Mescher and many others suspected that nuclein (nucleic acid) was associated in some way with cell inheritance, but the first direct evidence that DNA is the bearer of genetic information came in 1944 through a discovery made by Oswald T. Avery, Colin MacLeod, and Maclyn McCarty. These investigators found that DNA extracted from a virulent (disease-causing) strain of the bacterium Streptococcus pneumoniae, also known as pneumococcus, genetically transformed a nonvirulent strain of this organism into a virulent form (Fig. 8-12). 

In vivo and in vitro evidence that DNA causes transformation of Streptococcus pneumoniae, (a) Transformation experiment by Griffith. R bacteria are nonvirulent. S bacteria are virulent. A mixture of R bacteria and heat-killed S bacteria is also virulent if transformation has occurred. (b) Transformation experiment by Avery and coworkers. When bacteria from a liquid culture are spread on a semisolid medium, each cell adheres to the medium at random. As... 

A Severin, AM Figueiredo, A Tomasz. Separation of abnormal cell wall composition from penicillin-resistance through genetic transformation of Streptococcus pneumoniae. J Bacteriol 178 1788-1792, 1996. 

Barnes DM, Whittier S, Gilligan PH, Soares S, Tomasz A, Henderson FW. Transmission of multidrug-resistant serotype 23F Streptococcus pneumoniae in group day care evidence suggesting capsular transformation of the resistant strain in vivo. J Infect Dis 1995 171(4) 890-6. 

Hui FM, Morrison DA (1991) Genetic transformation in Streptococcus pneumoniae nucleotide sequence analysis shows comA, a gene required for competence induction, to be a member of the bacterial ATP-dependent transport protein family. J Bacteriol 173 372-381... 

However, the first mutants which were recognized as affecting mismatch repair were found in bacteria. The hex mutant of Streptococcus (Diplococcus) pneumoniae, which increases the transformation rate of certain markers a hundred-fold, was found to be a mutator. Transformation in S. pneumoniae involves the uptake of a single strand of donor DNA and efficiency is limited by the correction of the mutational difference between donor and recipient. In /iex-mutants, the directionality of this correction is abolished (Lacks, 1970). Subsequently a number of... 

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