CLINICAL CASES
101
B IO C H E M IS T R Y PE A R L S
The quinolone antibiotics target bacterial DNA gyrase in many
gram-negative bacteria.
Supercoiling is controlled by topoisomerases which alter the topol-
ogy of the circular DNA but not its covalent structure.
Type I topoisomerases relax DNA from negative supercoils
formed by the action of type II topoisomerase by creating tran-
sient single-strand breaks in DNA.
Type II topoisomerases (also called DNA gyrases) change DNA
topology by making transient double-strand breaks in DNA.
Histones are abundant proteins associated with eukaryotic DNA and
are a family of basic proteins rich in the positively charged amino
acids lysine and/or arginine, which interact with the negative
charges of DNA.
REFERENCES
Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell, 4th ed.
New York and London: Garland, 2002.
Lodish H, Berk A, Zipursky SL, et al. Molecular Cell Biology, 4th ed. New York:
Freeman, 2000.
Petri WA. Anti-microbial agents. In: Goodman AG, Gilman LS, eds. The Pharmacological
Basis of Therapeutics, 10th ed. New York: McGraw-Hill, 2001.
Prescott LM, Harley JP, Klein DA. Microbiology, 3rd ed. Boston, MA: W.C. Brown,
1996.
Voet D, Voet JG, Pratt, CW. Fundamentals of Biochemistry, upgrade ed. New York:
John Wiley, 2002.
previous page 115 Case Files   Biochemistry read online next page 117 Case Files   Biochemistry read online Home Toggle text on/off