A discussion of molecular biology methods for protein engineering

Highly efficient and simple SSPER and rrPCR approaches for the accurate site-directed mutagenesis of large and small plasmids

Advances are needed in the site-directed mutagenesis of large plasmids for protein structure-function studies, as current methods are often inefficient, complicated and time-consuming. Here two new methods are reported that overcome these difficulties, namely the single primer extension reaction (SSPER) strategy that reaches 100% efficiency and the reduce recycle PCR (rrPCR) method that is advantageous in generating single and pairwise combinations of mutations. Both methods are distinguished from current technologies by the addition of a step that easily removes the oligonucleotide primer(s) after the first reaction, thus allowing for the addition of a second reaction in chronological sequence to generate and isolate the appropriate DNA product with the site-directed mutation(s). High efficiency of the methods is demonstrated by generating single and paired combinations of the 11 site-directed mutations targeted on 5 different plasmid DNA templates ranging from 10 to 12 kb and 57-60% GC-content at a rate of 50-100%. Overall, the methods are demonstrated to be (i) highly accurate, allowing for screening of plasmids by DNA sequencing, (ii) streamlined to generate the mutations within a single day, (iii) cost-effective in requiring only two primers and two enzymes (DpnI and a proofreading DNA polymerase), (iv) straightforward in primer design, (v) applicable for both large and small plasmids, and (vi) easily implemented by entry level researchers.

Biopharmaceuticals from microorganisms: from production to purification

The use of biopharmaceuticals dates from the 19th century and within 5–10 years, up to 50% of all drugs in development will be biopharmaceuticals. In the 1980s, the biopharmaceutical industry experienced a significant growth in the production and approval of recombinant proteins such as interferons (IFN α, β, and γ) and growth hormones. The production of biopharmaceuticals, known as bioprocess, involves a wide range of techniques. In this review, we discuss the technology involved in the bioprocess and describe the available strategies and main advances in microbial fermentation and purification process to obtain biopharmaceuticals.

Biomedical techniques in translational studies: The journey so far

Biomedical techniques have wide clinical application in many fields of medicine such as oncology, rheumatology, immunology, genomics, cardiology and diagnostics; among others. This has been made possible with the use of genetic engineering and a number of techniques like Immunohistochemistry (IHC), Fluorescent Microscopy, Cell Culture, Genetically Modified (GM) Cells, Monoclonal Antibodies (MAbs), Polymerase Chain Reaction (PCR) and Western blotting. The aim of this literature review is to explore the foundations and bases of the commonly used biomedical techniques, as well as their applications in biomedical research and clinical medicine in general. This review also aims to shed some light on more recent advances in genetic engineering, especially in relation to genetically modified cells and use of monoclonal antibodies which have found more increasing use and relevance in genomics, oncology, rheumatology, immunology, cardiology as well as diagnostics, and have revolutionised patient care, while at the same time resulting in improved standard of health care. Unfortunately, some of these new techniques are associated with unwanted side effects which may pose a risk to the people they are actually intended for. Therefore, there is need for strict regulations and guidelines to control the use and implementation of some of these novel techniques.

SOMA: a single oligonucleotide mutagenesis and cloning approach

Modern biology research requires simple techniques for efficient and restriction site-independent modification of genetic material. Classical cloning and mutagenesis strategies are limited by their dependency on restriction sites and the use of complementary primer pairs. Here, we describe the Single Oligonucleotide Mutagenesis and Cloning Approach (SOMA) that is independent of restriction sites and only requires a single mutagenic oligonucleotide to modify a plasmid. We demonstrate the broad application spectrum of SOMA with three examples. First, we present a novel plasmid that in a standardized and rapid fashion can be used as a template for SOMA to generate GFP-reporters. We successfully use such a reporter to assess the in vivo knock-down quality of morpholinos in Xenopus laevis embryos. In a second example, we show how to use a SOMA-based protocol for restriction-site independent cloning to generate chimeric proteins by domain swapping between the two human hRMD5a and hRMD5b isoforms. Last, we show that SOMA simplifies the generation of randomized single-site mutagenized gene libraries. As an example we random-mutagenize a single codon affecting the catalytic activity of the yeast Ssy5 endoprotease and identify a spectrum of tolerated and non-tolerated substitutions. Thus, SOMA represents a highly efficient alternative to classical cloning and mutagenesis strategies.