Micrococcin P1 - A bactericidal thiopeptide active against Mycobacterium tuberculosis.

The lack of proper treatment for serious infectious diseases due to the emergence of multidrug resistance reinforces the need for the discovery of novel antibiotics. This is particularly true for tuberculosis (TB) for which 3.7% of new cases and 20% of previously treated cases are estimated to be caused by multi-drug resistant strains.

Organization of ribosomes and nucleoids in Escherichia coli cells during growth and in quiescence.

We have examined the distribution of ribosomes and nucleoids in live Escherichia coli cells under conditions of growth, division, and in quiescence. In exponentially growing cells translating ribosomes are interspersed among and around the nucleoid lobes, appearing as alternative bands under a fluorescence microscope. In contrast, inactive ribosomes either in stationary phase or after treatment with translation inhibitors such as chloramphenicol, tetracycline, and streptomycin gather predominantly at the cell poles and boundaries with concomitant compaction of the nucleoid.

Mechanism of elongation factor-G-mediated fusidic acid resistance and fitness compensation in Staphylococcus aureus.

Antibiotic resistance in bacteria is often associated with fitness loss, which is compensated by secondary mutations. Fusidic acid (FA), an antibiotic used against pathogenic bacteria Staphylococcus aureus, locks elongation factor-G (EF-G) to the ribosome after GTP hydrolysis. To clarify the mechanism of fitness loss and compensation in relation to FA resistance, we have characterized three S.

Structure and function of FusB: an elongation factor G-binding fusidic acid resistance protein active in ribosomal translocation and recycling.

Fusidic acid (FA) is a bacteriostatic antibiotic that locks elongation factor G (EF-G) to the ribosome after GTP hydrolysis during elongation and ribosome recycling. The plasmid pUB101-encoded protein FusB causes FA resistance in clinical isolates of Staphylococcus aureus through an interaction with EF-G. Here, we report 1.

Bacterial ribosome requires multiple L12 dimers for efficient initiation and elongation of protein synthesis involving IF2 and EF-G.

The ribosomal stalk in bacteria is composed of four or six copies of L12 proteins arranged in dimers that bind to the adjacent sites on protein L10, spanning 10 amino acids each from the L10 C-terminus. To study why multiple L12 dimers are required on the ribosome, we created a chromosomally engineered Escherichia coli strain, JE105, in which the peripheral L12 dimer binding site was deleted. Thus JE105 harbors ribosomes with only a single L12 dimer.

The ribosome-bound Hsp70 homolog Ssb of Saccharomyces cerevisiae.

The Hsp70 homolog Ssb directly binds to the ribosome and contacts a variety of newly synthesized polypeptide chains as soon as they emerge from the ribosomal exit tunnel. For this reason a general role of Ssb in the de novo folding of newly synthesized proteins is highly suggestive. However, for more than a decade client proteins which require Ssb for proper folding have remained elusive.

Ribosome-associated complex binds to ribosomes in close proximity of Rpl31 at the exit of the polypeptide tunnel in yeast.

Ribosome-associated complex (RAC) consists of the Hsp40 homolog Zuo1 and the Hsp70 homolog Ssz1. The chaperone participates in the biogenesis of newly synthesized polypeptides. Here we have identified yeast Rpl31, a component of the large ribosomal subunit, as a contact point of RAC at the polypeptide tunnel exit.

Functional characterization of the atypical Hsp70 subunit of yeast ribosome-associated complex.

Eukaryotic ribosomes carry a stable chaperone complex termed ribosome-associated complex consisting of the J-domain protein Zuo1 and the Hsp70 Ssz1. Zuo1 and Ssz1 together with the Hsp70 homolog Ssb1/2 form a functional triad involved in translation and early polypeptide folding processes. Strains lacking one of these components display slow growth, cold sensitivity, and defects in translational fidelity.