Localization of proteins to the 1,2-propanediol utilization microcompartment by non-native signal sequences is mediated by a common hydrophobic motif.
Various bacteria localize metabolic pathways to proteinaceous organelles known as bacterial microcompartments (MCPs), enabling the metabolism of carbon sources to enhance survival and pathogenicity in the gut. There is considerable interest in exploiting bacterial MCPs for metabolic engineering applications, but little is known about the interactions between MCP signal sequences and the protein shells of different MCP systems. We found that the N-terminal sequences from the ethanolamine utilization (Eut) and glycyl radical-generating protein MCPs are able to target reporter proteins to the 1,2-propanediol utilization (Pdu) MCP, and that this localization is mediated by a conserved hydrophobic residue motif. Recapitulation of this motif by the addition of a single amino acid conferred targeting function on an N-terminal sequence from the ethanol utilization MCP system that previously did not act as a Pdu signal sequence. Moreover, the Pdu-localized signal sequences competed with native Pdu targeting sequences for encapsulation in the Pdu MCP. Salmonella enterica natively possesses both the Pdu and Eut operons, and our results suggest that Eut proteins might be localized to the Pdu MCP in vivo. We further demonstrate that S. enterica LT2 retained the ability to grow on 1,2-propanediol as the sole carbon source when a Pdu enzyme was replaced with its Eut homolog. Although the relevance of this finding to the native system remains to be explored, we show that the Pdu-localized signal sequences described herein allow control over the ratio of heterologous proteins encapsulated within Pdu MCPs.
From the Department of Chemical and Biomolecular Engineering and.
Christopher M
CM
Jakobson
From the Department of Chemical and Biomolecular Engineering and.
Edward Y
EY
Kim
From the Department of Chemical and Biomolecular Engineering and.
Marilyn F
MF
Slininger
Biophysics Graduate Group, University of California, Berkeley, California 94720.
Alex
A
Chien
From the Department of Chemical and Biomolecular Engineering and dtercek@berkeley.edu.
Danielle
D
Tullman-Ercek
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D001667:Binding, Competitive; D002244:Carbon / Q000737:chemistry; D003013:Clostridium / Q000235:genetics; D019856:Ethanolamine / Q000737:chemistry; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D057927:Hydrophobic and Hydrophilic Interactions; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009876:Operon; D019946:Propylene Glycol / Q000737:chemistry*; D011485:Protein Binding; D015202:Protein Engineering / Q000379:methods; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D019779:Salmonella enterica / Q000737:chemistry* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013347:Subcellular Fractions; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D021382:Protein Sorting Signals; D019856:Ethanolamine; D019946:Propylene Glycol; D002244:Carbon
1,2-propanediol utilization; Salmonella enterica; bacterial metabolism; bacterial microcompartments; ethanolamine utilization; protein targeting; subcellular organelle; synthetic biology