Part:BBa_K1668003

orfX (from Streptomyces avermitilis, increasing avermectin production)

The part orfX is a putative membrane-bound putative regulatory gene and its product is a putative membrane protein.

This gene sequence could not function in E.coli. If you would like to express frr in Streptomyces avermitilis, remember to add ermEp [1] as its promoter.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  INCOMPATIBLE WITH RFC[12]

  Illegal NotI site found at 160
  Illegal NotI site found at 247
  Illegal NotI site found at 361
  Illegal NotI site found at 595
  Illegal NotI site found at 745
  
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal XhoI site found at 510
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal NgoMIV site found at 463
  Illegal AgeI site found at 264
  
• 1000
  INCOMPATIBLE WITH RFC[1000]

  Illegal BsaI site found at 441
  Illegal BsaI.rc site found at 195
  

Characterization

BACKGROUND

orfX is a putative membrane-bound putative regulatory gene and its product is a putative membrane protein.

Function

The results of PCR analysis and the gene disruption experiments strongly suggest that either a considerably conserved sequence of orfX or a combination of orfX and other assisting genes exists in the high producers. And the orfX product appears to play an essential role in the production and regulation of avermectin in both the normal strain and the high producers. When wild-type S. avermitilis was transformed with a 8.0-kb DNA fragment containing the orfX gene, avermectin production increased approximately 3.5-fold. However, the nature of the stimulatory effect of orfX is still unclear.

Principle

The orfX gene reveals a “copy number effect”. That is to say, multiple fragment copies can substantially increase avermectin production in S. avermitilis. Different from metK and frr gene, the DNA fragment containing orfX gene also increased avermectin bio-synthesis in various S. avermitilis strains, including the high-producing mutant strain ATCC 31780 and a semi-industrial strain L-9.

RESULTS

Gel electrophoretic analysis

Fig.2 Gel electrophoretic analyses of PCR products (A) and selected examples of cloned products of seamless assembly reaction (B)

In Fig.2, (A) 5-μl samples of the PCR products for orfX, (B) 5-μl samples of the bacteria solution PCR products were loaded onto a 1% BioRad Ready Agarose Mini Gel, then subjected to AGE. See (protocol) for AGE parameters. The DNA size standards was the DL1,000 DNA Marker (M1; Takara, Cat#3428A) and DL2,000 DNA Marker (M2; TaKaRa, Cat#3427A) . Bands were visualized with a Shanghai Peiqing JS-380A Fluorescence Imager. PCR products, positive clones and negative clones are indicated.

DNA sequencing

We have sequenced the parts with standard primers VF2 and VR. The sequence of the 942bp part shows 100% agreement with the desired sequence.

REFERENCE

Hwang, Y. S., et al. (2003). "Cloning and Analysis of a DNA Fragment Stimulating Avermectin Production in Various Streptomyces avermitilis Strains." Appl Environ Microbiol 69(2): 1263-1269.