Fever, Rash, and Cough in a 7-Year-Old Boy.

A 7-year-old boy presented to the emergency department with fever, cough, congestion, abdominal pain, myalgias, and morbilliform rash. Several aspects of the patient's history, including recent travel, living on a farm, exposure to sick contacts, and new medications, resulted in a wide differential diagnosis. Initial laboratory testing revealed leukocytosis with neutrophilia and elevated atypical lymphocytes, but did not reveal any infectious causes of illness.

Analysis of the linker region joining the adenylation and carrier protein domains of the modular nonribosomal peptide synthetases.

Nonribosomal peptide synthetases (NRPSs) are multimodular proteins capable of producing important peptide natural products. Using an assembly line process, the amino acid substrate and peptide intermediates are passed between the active sites of different catalytic domains of the NRPS while bound covalently to a peptidyl carrier protein (PCP) domain. Examination of the linker sequences that join the NRPS adenylation and PCP domains identified several conserved proline residues that are not found in standalone adenylation domains.