<jats:title>Summary</jats:title><jats:p>The transcriptional and translational control of the biosynthesis of the β‐lactamase inhibitor clavulanic acid is a subject of great scientific and industrial interest. To study the role of the ribosomal protein L11 on control of clavulanic acid gene transcription, the DNA region <jats:italic>aspC‐tRNA</jats:italic><jats:sup><jats:italic>trp</jats:italic></jats:sup><jats:italic>‐secE‐rplK‐rplA‐rplJ‐rplL</jats:italic> of <jats:italic>Streptomyces clavuligerus</jats:italic> was cloned and characterized. An <jats:italic>S. clavuligerus rplK</jats:italic><jats:sup>ΔPALG</jats:sup> mutant, with an internal 12 nucleotides in‐frame deletion in the <jats:italic>rplK</jats:italic> gene, encoding the L11 (RplK) ribosomal protein lacking amino acids <jats:sup>29</jats:sup>PALG<jats:sup>32</jats:sup>, was constructed by gene replacement. This deletion alters the L11 N‐terminal domain that interacts with the RelA and class I releasing factors‐mediated translational termination. The mutant grew well, showed threefold higher resistance to thiostrepton, did not form spores and lacked diffusible brown pigments, as compared with the wild‐type strain. The wild‐type phenotype was recovered by complementation with the native <jats:italic>rplK</jats:italic> gene. <jats:italic>S. clavuligerus rplK</jats:italic><jats:sup>ΔPALG</jats:sup> produced reduced levels of clavulanic acid (15–26% as compared with the wild type) and cephamycin C (40–50%) in cultures grown in defined SA and complex TSB media. The decreased yields resulted from an impaired transcription of the regulatory genes <jats:italic>ccaR</jats:italic> and <jats:italic>claR</jats:italic> and the <jats:italic>cefD</jats:italic> and <jats:italic>ceaS2</jats:italic> genes for cephamycin and clavulanic acid biosynthesis respectively. Expression of <jats:italic>ceaS2</jats:italic> encoding <jats:styled-content>c</jats:styled-content>arboxy<jats:styled-content>e</jats:styled-content>thyl<jats:styled-content>a</jats:styled-content>rginine <jats:styled-content>s</jats:styled-content>ynthase (CEAS), the precursor‐committing enzyme for clavulanic acid biosynthesis, was particularly affected in this mutant. In the wild‐type strain polyphosphorylated nucleotides peaked at 36–48 h of growth in SA cultures whereas expression of the cephamycin and clavulanic acid genes occurred 12–24 h earlier than the increase in ppGpp indicating that there is no strict correlation between the peak of ppGpp and the onset of transcription of the clavulanic acid and cephamycin C biosynthesis. The drastic effect of the <jats:italic>rplK</jats:italic><jats:sup>ΔPALG</jats:sup> mutation on the onset of expression of the <jats:italic>ceaS2</jats:italic> and the regulatory <jats:italic>ccaR</jats:italic> and <jats:italic>claR</jats:italic> genes and the lack of correlation with ppGpp levels suggest that the onset of transcription of these genes is modulated by the conformational alteration of the N‐terminal region of L11 probably by interaction with the nascent peptide releasing factors and with RelA.