Antibiotics Targeting Ribosomes
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چکیده
The charge separation across the membrane is performed by a set of cofactors termed the electron transfer chain (Figure 9). It consists of three pairs of chlorophylls and one pair of phylloquinones (Vitamin K1), positioned along the pseudo-C2 axis in two branches, followed by the 4Fe4S cluster FX that is located right on the pseudo-C2 axis and coordinated to both PsaA and PsaB.The electron is further transferred to the two terminal 4Fe4S clusters FA and FB located in the stromal subunit PsaC. The light energy required to drive this process is captured by the integral antenna system containing 90 chlorophyll a and 22 carotenoids (Figure 9). The crystal structure of PSI shows new types of Mg2+ axial ligands, not previously observed in the structures of other (bacterio)chlorophyll-protein complexes, the most striking being a phospholipid oxygen and methionine sulphur.
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Antibiotics targeting ribosomes: resistance, selectivity, synergism and cellular regulation.
Antibiotics target ribosomes at distinct locations within functionally relevant sites. They exert their inhibitory action by diverse modes, including competing with substrate binding, interfering with ribosomal dynamics, minimizing ribosomal mobility, facilitating miscoding, hampering the progression of the mRNA chain, and blocking the nascent protein exit tunnel. Although the ribosomes are hig...
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