title: The response of Lactococcus lactis to membrane protein production.
abstract: BACKGROUND
  The biogenesis of membrane proteins is more complex than that of water-soluble proteins, and recombinant expression of membrane proteins in functional form and in amounts high enough for structural and functional studies is often problematic. To better engineer cells towards efficient protein production, we set out to understand and compare the cellular consequences of the overproduction of both classes of proteins in Lactococcus lactis, employing a combined proteomics and transcriptomics approach.
  
  
  RESULTS
  Highly overproduced and poorly expressed membrane proteins both resulted in severe growth defects, whereas amplified levels of a soluble substrate receptor had no effect. In addition, membrane protein overproduction evoked a general stress response (upregulation of various chaperones and proteases), which is probably due to accumulation of misfolded protein. Notably, upon the expression of membrane proteins a cell envelope stress response, controlled by the two-component regulatory CesSR system, was observed.
  
  
  CONCLUSIONS
  The physiological response of L. lactis to the overproduction of several membrane proteins was determined and compared to that of a soluble protein, thus offering better understanding of the bottlenecks related to membrane protein production and valuable knowledge for subsequent strain engineering.
authors: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands.
authors: Ravi K R
authors: RK
authors: Marreddy
authors: Joao P C
authors: JP
authors: Pinto
authors: Justina C
authors: JC
authors: Wolters
authors: Eric R
authors: ER
authors: Geertsma
authors: Fabrizia
authors: F
authors: Fusetti
authors: Hjalmar P
authors: HP
authors: Permentier
authors: Oscar P
authors: OP
authors: Kuipers
authors: Jan
authors: J
authors: Kok
authors: Bert
authors: B
authors: Poolman
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics / Q000502:physiology; D013294:Lactococcus lactis / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins