N3011 FAQs for Lambda DNA, Cloning and Mutagenesis, Intl, NEB
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Lambda DNA FAQ

Q1: What are the Lambda DNA cohesive ends?
Q2: Is your Lambda DNA linear or circular?
Q3: What are the mutations in your lambda DNA?
Q4: Is the Lambda DNA (N3011) methylated?

Q1: What are the Lambda DNA cohesive ends?

A1: The Lambda DNA has 12 base, single-stranded overhangs that are complementary. Their sequences are:


Q2: Is your Lambda DNA linear or circular?

A2: Our lambda DNA is linear. We do not sell Lambda DNA in a circular form. Theoretically, it could be ligated to form circles but, due to its large size, it is difficult to achieve. The likelihood of ends of several separated Lambda DNA molecules finding each other are far greater than one single piece of Lambda DNA folding back on itself, unless the solution is very dilute.

Q3: What are the mutations in your lambda DNA?

A3: Our Lambda DNA contains a total of 4 mutations:
-ind1 at 37,589 C->T, which creates a Hind III site at 37,584.
-Sam7 at 45,352 G->A.

Sam7 is an amber mutation in a gene involved in lysis of the bacterial cell membrane. The absence of a wild-type S gene product leads to an intracellular accumulation of infectious bacteriophage particles.
-cI857 at 37,742 C->T.

cI857 is a temperature sensitive mutation that renders the CI gene product thermo labile.
-cI857s7 strain also carries a G->A mutation at 43,082.

Q4: Is the Lambda DNA (N3011) methylated?

A4: Yes, it is but we do not know exactly which A and C sites get methylated since the methylation in Lambda is not 100% done. It is dam+, dcm+, EcoK- (strain C190). We do sell N6-methyladenine-free Lambda DNA (N3013), which is dam-, dcm+, EcoK+ (strain GM33).

The methylase encoded by the dam gene (Dam methylase) transfers a methyl group to the N6 position of the adenine residues in the sequence GATC (1,2). The Dcm methylase, encoded by the dcm gene, methylates the internal cytosine residues in the sequences CCAGG and CCTGG (1,3) at the C5 position. The EcoKI methylase, M.EcoKI, modifies adenine residues in the sequences AAC(N6)GTGC and GCAC(N6)GTT.

Not all DNA isolated from E.coli is methylated to the same extent. While pBR322 DNA is fully modified, only about 50% of Lambda DNA Dam sites are methylated, presumably because the methylase does not have the opportunity to methylate the DNA fully before it is packaged into the phage head.