Breaking News
February 18, 2019 - New dental adhesive prevents tooth decay around orthodontic brackets
February 18, 2019 - New eHealth tool shows potential to improve quality of asthma care
February 18, 2019 - New Australian initiative helps emergency clinicians to improve patient care
February 17, 2019 - Apellis Pharmaceuticals’ APL-2 Receives Fast Track Designation from the FDA for the Treatment of Patients with Paroxysmal Nocturnal Hemoglobinuria
February 17, 2019 - Researchers identify faulty ‘brake’ that interferes with heart muscle’s ability to contract and relax
February 17, 2019 - Support from trusted adults can reduce risk of dying in suicidal teens, finds study
February 17, 2019 - Heart attack awareness improved since 2008
February 17, 2019 - Exercise gives a better brain boost to older men than women
February 17, 2019 - New research disproves previous assumptions of how looks influence personality
February 17, 2019 - Cannabis use as a teenager linked to depression later in life
February 17, 2019 - Sinks by Toilets in ICU Patient Rooms Harbor Harmful Bacteria
February 17, 2019 - Cancer cells’ plasticity makes them harder to stop
February 17, 2019 - Young cannabis users have increased risk of depression and suicidal behavior
February 17, 2019 - Tasmanian Devils Likely to Survive Cancer Scourge
February 17, 2019 - Neoadjuvant PD-1 blockade seems effective in glioblastoma
February 17, 2019 - Personal, social factors play role in enabling sustainable return to work after ill health
February 17, 2019 - Mouse studies show ‘inhibition’ theory of autism wrong
February 17, 2019 - Study shows how neuroactive steroids inhibit activity of pro-inflammatory proteins
February 17, 2019 - Use of liver grafts from older donors decreased despite better outcomes in recipients
February 17, 2019 - MUSC researchers discover new mechanism for a class of anti-cancer drugs
February 17, 2019 - HPV misconceptions are causing women to miss smear tests
February 17, 2019 - Sanofi and Regeneron Offer Praluent (alirocumab) at a New Reduced U.S. List Price
February 17, 2019 - Researchers say auditory testing can identify children for autism screening
February 17, 2019 - New method analyzes how single biological cells react to stressful situations
February 17, 2019 - WVU gynecologic oncologist investigates novel treatment for cervical and vaginal cancers
February 17, 2019 - ADHD diagnoses poorly documented
February 17, 2019 - Majority of gender minority youth do not identify with traditional sexual identity labels
February 17, 2019 - AbbVie, Teneobio enter into strategic transaction to develop potential treatment for multiple myeloma
February 17, 2019 - Lower Birth Weight May Up Risk for Psychiatric Disorders
February 17, 2019 - Scientists identify reversible molecular defect underlying rheumatoid arthritis
February 17, 2019 - Moffitt researchers shed light on how CAR T cells function mechanistically
February 16, 2019 - Female Anatomy May Play Big Role in Sperm’s Success
February 16, 2019 - BMI may mediate inverse link between fiber intake, knee OA
February 16, 2019 - Movement impairments in autism can be reversed through behavioral training
February 16, 2019 - Studies address racial disparities in postpartum period and cardiovascular health
February 16, 2019 - Scientists implicate hidden genes in the severity of autism symptoms
February 16, 2019 - Decreased deep sleep linked to early signs of Alzheimer’s disease
February 16, 2019 - Neuroscientists show how the brain responds to texture
February 16, 2019 - Gilead Announces Topline Data From Phase 3 STELLAR-4 Study of Selonsertib in Compensated Cirrhosis (F4) Due to Nonalcoholic Steatohepatitis (NASH)
February 16, 2019 - What Can I Do About Sweating? (for Teens)
February 16, 2019 - Companies navigate dementia conversations with older workers
February 16, 2019 - Newly developed stem cell technologies show promise for treating PD patients
February 16, 2019 - Collaborative material research could advance self-assembling nanomaterials
February 16, 2019 - Researchers take major step in creating technology that mimics the human brain
February 16, 2019 - Erasing memories associated with cocaine use reduces drug seeking behavior
February 16, 2019 - Artificial intelligence can accurately predict prognosis of ovarian cancer patients
February 16, 2019 - Racial disparities in cancer deaths on the decline for America
February 16, 2019 - FDA authorizes new interoperable insulin pump for children, adults with diabetes
February 16, 2019 - Coexisting Medical Conditions, Smoking Explain PTSD-CVD Link
February 16, 2019 - Skin Cancer Screening: MedlinePlus Lab Test Information
February 16, 2019 - ‘Happiness’ exercises can boost mood in those recovering from substance use disorder
February 16, 2019 - Cell manipulation could soon halt or reverse aging
February 16, 2019 - Pumped Breast Milk Falls Short of Breastfed Version
February 16, 2019 - Men’s porn habits could fuel partners’ eating disorders, study suggests
February 16, 2019 - Rapid progression of age-related diseases may result from formation of vicious cycles
February 16, 2019 - Immune checkpoint molecule protects against future development of cancer
February 16, 2019 - New method produces hydrogels that have properties similar to cells’ environment
February 16, 2019 - $4.1 million funding for heart research on Valentine’s Day
February 16, 2019 - General anesthesia in early infancy unlikely to have lasting effects on developing brains
February 16, 2019 - New breakthroughs for muscular dystrophy research
February 16, 2019 - First Opinion: Embryo editing for higher IQ is a fantasy. Embryo profiling for it is almost here
February 16, 2019 - Vapers develop cancer-related gene deregulation as cigarette smokers
February 16, 2019 - Bringing Antimicrobial Susceptibility Testing (AST) to the Community
February 16, 2019 - Decolonization protocol after hospital discharge can prevent dangerous infections
February 16, 2019 - Children with ASD more likely to face maltreatment, study finds
February 16, 2019 - Study finds genetic vulnerability to use of menthol cigarettes
February 16, 2019 - Promising drug developed to rejuvenate muscle cells
February 16, 2019 - H-RT should be the standard of care for men with low risk prostate cancer, study shows
February 16, 2019 - New technique using patients’ own modified cells could help treat Crohn’s disease
February 16, 2019 - Therapeutic endoscopy has an expanding role in the treatment of IBD
February 16, 2019 - Blood clot discovery could lead to development of better treatments for blood diseases
February 16, 2019 - Intervention can increase exclusive breastfeeding rates
February 16, 2019 - New project explores how gaming technologies can help cancer patients communicate better
February 16, 2019 - Catalyst Biosciences Presents Updated Data from Its Phase 2/3 Trial of Subcutaneous Marzeptacog Alfa (Activated) in Individuals with Hemophilia A or B with Inhibitors at the 12th Annual EAHAD Congress
February 16, 2019 - Rerouting nerves during amputation reduces phantom limb pain before it starts
February 16, 2019 - A Hormone Produced When We Exercise Might Help Fight Alzheimer’s
February 16, 2019 - Millions of British people breathe toxic air travelling to GPs
February 16, 2019 - Conformance of genetic characteristics found to be crucial for longer preservation of kidney graft
February 16, 2019 - Researchers use optogenetic tool to control, visualize receptor signals in neural cells
February 16, 2019 - New reversible antiplatelet therapy could reduce risk of blood clots, prevent cancer metastasis

Molecular details of protein crystal nucleation uncovered

image_pdfDownload PDFimage_print

Dr. Mike Sleutel (VIB-VUB): “It will be exciting to see this new technique being applied in the future to follow protein self-assembly processes that are implicated in a range of pathological disorders, such as liquid-liquid phase separation in eye cataract formation or the formation of amyloid fibers associated with a range of neurological disorders.” The Nature article can be accessed here.

 

Medical importance of protein crystals

Protein crystals bear great medical and scientific relevance. For decades, they have been essential for structural biologists to solve the three-dimensional structures of proteins, but protein crystals are also used as bio-pharmaceutical delivery agents. Crystalline suspensions are attractive formulations to store and administer active pharmaceutical compounds because of their long-term shelf life, low solvent viscosity, and slow dissolution rate. Perhaps the best known example is insulin: insulin shots comprise the subcutaneous injection of a suspension of insulin microcrystals which dissolve slowly to yield a steady and sustained delivery over time. Despite their tremendous potential, there are two factors that limit the use of protein crystals in a broad range of applications.

 

Challenges in developing protein crystals

First, growing protein crystals, as many molecular biologists will say, is more an art than a science. In fact, for many proteins, crystallization can be excruciatingly difficult. This in part follows from the fact that scientists don’t understand the early stages of protein crystal formation. Any crystal originates from a nucleus, a tiny crystalline seed, which forms by the spontaneous grouping of a few molecules in solution that have to adopt a regular organization in three-dimensions. How the molecules realize this improbable feat has remained a mystery up until this point.

Secondly, a single protein can crystallize in multiple different crystal forms, this is known as polymorphism. Different crystal polymorphs have different characteristics, with the most notable ones the power to diffract X-rays (crucial for 3D structure determination), and the rate at which it dissolves (crucial for drug delivery). As of yet, it is very difficult to guide the crystallization process to the polymorph of one’s liking. Scientists believe that polymorph selection takes place at the stage of nucleation, but no one knows exactly how the mechanism works.

 

A new way to look at the self-assembly of macromolecules

The group of scientists lead by Dr. Mike Sleutel have used state-of-the-art cryo-transmission electron microscopy (Cryo-TEM) to capture the birth of a protein crystal by visualizing the process of nucleation at molecular resolution.

Dr. Heiner Friedrich explains: “Because the process happens so rapidly, and at such a small length scale we needed to cryogenically arrest the sample at various stages of the process. Once frozen in time, we use a very sensitive electron microscope to visualize the proteins and how they group together to form a nucleus and finally the protein crystal.”

By analyzing the Cryo-TEM images taken from a series of samples at constant time intervals, they could start to puzzle together the series of molecular collisions that need to take place to form a crystalline nucleus. Dr. Mike Sleutel continues: “We were struck by the unexpected complexity of the process, which proved to be far more intricate than the working models we and other in the field had prior to these observations. For the protein that we used in our study we uncovered a hierarchical self-assembly process that involves three subsequent stages of self-assembly at ever increasing length scales.” These observations are the first of their kind and provide an new way to look at the self-assembly processes of macromolecules into larger structures.

But the team went even one step further, and compared the nucleation pathways of multiple polymorphs. They showed that polymorph selection is dictated by the architecture of the smallest possible fragments formed at early time-points. Once such structures are formed, the faith of the system is set. Dr. Alexander Van Driessche explains: “By analyzing and understanding the differences in structure of the various nuclei, we developed strategies to guide the polymorph selection process. We achieved this by gently tweaking the different modes of interaction that exist between the molecules, steering the nucleation process in the direction of our choosing.” The team believes that the new insights and methodology will significantly advance the development of protein crystals for 3D structure determination and medical applications.

Dr. Mike Sleutel works in the Han Remaut lab in the VIB-VUB Center for Structural Biology

Tagged with:

About author

Related Articles