A Life in Bioinorganic Chemistry: a Q&A Interview with Stefano Ciurli
Interviewer: Professor Ciurli, before we speak about nickel enzymes and bioinorganic chemistry, let us begin earlier. What kind of upbringing shaped your curiosity?
Stefano Ciurli: I grew up in Italy in an environment where education, discipline, and intellectual curiosity were important values. I was not “born” into bioinorganic chemistry, of course. That came much later. But from early on I was attracted to understanding how things work at a fundamental level. Chemistry appealed to me because it offered a language to explain matter, transformation, structure, and reactivity. It was both concrete and deeply conceptual.
Interviewer: Was there a moment when you realized that chemistry would become your path?
Stefano Ciurli: It was a gradual process. Like many young students, I was initially fascinated by the explanatory power of science. But chemistry had something special for me: it connected the visible world with invisible molecular events. Once I understood that the properties of materials, reactions, enzymes, and even living systems could be interpreted through molecular structure and bonding, I felt that chemistry was the right place for me.
Interviewer: You studied chemistry at the University of Pisa. How important was that period?
Stefano Ciurli: It was decisive. My years in Pisa gave me a rigorous foundation in inorganic chemistry, coordination chemistry, and physical reasoning. I learned that good chemistry requires both imagination and discipline: imagination to ask new questions, and discipline to answer them properly. That combination has remained important throughout my career.
Interviewer: Your early scientific steps were in synthetic inorganic chemistry. How do you remember that phase?
Stefano Ciurli: With great appreciation. My first work was rooted in coordination and synthetic inorganic chemistry, including metal complexes and porphyrin chemistry. That training was extremely valuable. It taught me to think carefully about metal ions, ligands, geometry, electronic structure, and reactivity. Even when I later moved toward proteins and biology, that chemical way of thinking remained central.
Interviewer: Your experience abroad also seems to have been important. What did it give you scientifically?
Stefano Ciurli: Working in international research environments early in my career broadened my scientific horizon. It showed me that research was not simply the continuation of study; it was a way of asking new questions. It also exposed me to high standards of rigor, originality, and independence. Those experiences helped me understand what it means to build a scientific identity.
Interviewer: You later moved toward bioinorganic chemistry. Was that a sudden transition?
Stefano Ciurli: No, it was progressive. I did not move abruptly from chemistry to biology. The transition happened naturally. First came coordination chemistry and metal clusters. Then came metalloproteins, spectroscopy, redox proteins, and eventually enzymes and maturation systems. Bioinorganic chemistry became the natural meeting point of those experiences.
Interviewer: How did your early work on metal clusters and metalloproteins influence your later career?
Stefano Ciurli: Metal clusters are among the most beautiful examples of inorganic chemistry in biology. They are structurally precise, electronically rich, and biologically essential. Studying them helped me understand that metal sites in proteins are not decorative elements; they perform sophisticated chemical tasks. That idea stayed with me and later influenced my approach to nickel enzymes, urease, hydrogenase, and metallochaperones.
Interviewer: You became an independent scientist relatively early. How did that stage shape you?
Stefano Ciurli: The early years of independence are crucial. One has to build a laboratory, attract students, find funding, publish, collaborate, and define questions that are both feasible and meaningful. I was fortunate to have excellent mentors and collaborators, but it was still necessary to develop my own scientific voice. That is one of the most delicate steps in a scientist’s career.
Interviewer: What were the first major scientific questions you wanted to pursue independently?
Stefano Ciurli: I was interested in how metal centers determine biological function. Initially, that meant studying redox proteins, heme proteins, iron–sulfur proteins, and electron-transfer systems. Over time, the focus shifted toward nickel-dependent enzymes and the machinery that assembles them. The common thread was always the same: how does the inorganic element of a protein control its biological role?
Interviewer: Much of your scientific identity is associated with nickel enzymes. Why nickel?
Stefano Ciurli: Nickel is a remarkable metal in biology. It is not as abundant or universally used as iron or zinc, but where it appears, it often plays very specialized roles. Enzymes such as urease and hydrogenase are beautiful examples: they depend on nickel for catalysis, but the cell must also avoid nickel toxicity. That creates a fascinating biological problem. How does the cell acquire nickel, insert it into the correct protein, prevent mis-metalation, and regulate everything with precision? These questions have guided a large part of my research.
Interviewer: Urease has been one of the central systems in your work. What makes it such an important enzyme?
Stefano Ciurli: Urease is chemically elegant and biologically important. It catalyzes the hydrolysis of urea, a deceptively simple reaction with major implications in agriculture, medicine, and microbial physiology. In pathogens such as Helicobacter pylori, urease is essential for survival in acidic environments. From a chemical perspective, it is also a sophisticated dinuclear nickel enzyme, requiring not only the correct active-site architecture but also an elaborate maturation machinery. Understanding urease means understanding catalysis, metal trafficking, protein assembly, and pathogenicity.
Interviewer: Your work has often focused not only on enzymes themselves, but also on their maturation. Why is that aspect so important?
Stefano Ciurli: A metalloenzyme does not become active simply because the apoprotein exists and the metal is present. The metal has to be delivered to the correct site, often through dedicated accessory proteins. In the case of nickel enzymes, this process is highly controlled. Proteins such as HypA, UreE, and other maturation factors act as metallochaperones, scaffolds, regulators, or GTP-dependent machines. These proteins are not peripheral details; they are essential to biological function. They reveal how chemistry is organized inside the cell.
Interviewer: What has studying Helicobacter pylori taught you about metal homeostasis?
Stefano Ciurli: H. pylori is an extraordinary model because it depends heavily on nickel enzymes, especially urease and hydrogenase, while living in a hostile environment. It needs nickel, but nickel is also potentially toxic. This creates a delicate equilibrium. The organism must sense, import, allocate, and detoxify metals with high specificity. Studying H. pylori has shown us that metal homeostasis is not simply about availability; it is about timing, localization, protein dynamics, and competition among metal-binding sites.
Interviewer: How has your view of metallochaperones changed over the years?
Stefano Ciurli: At first, one might think of metallochaperones as simple carriers: they bind a metal and deliver it elsewhere. But they are much more than that. They are molecular decision-makers. They discriminate among metals, recognize partner proteins, respond to cellular conditions, and sometimes control the assembly of complex active sites. They often operate through weak, transient, and dynamic interactions. This makes them challenging to study, but also extremely interesting.
Interviewer: Your research combines many techniques: structural biology, NMR, SAXS, calorimetry, spectroscopy, and computational methods. How do you decide which method to use?
Stefano Ciurli: The biological question should dictate the method. No single technique is sufficient. X-ray crystallography or cryo-EM can provide high-resolution structures, but proteins are dynamic molecules. NMR can reveal motions, conformational equilibria, and metal-induced changes in solution. SAXS gives information on global shape and flexibility. ITC provides thermodynamics and, in some cases, kinetic insight. Spectroscopy informs us about metal coordination. The real power comes from integration. Bioinorganic chemistry is most convincing when structure, dynamics, thermodynamics, and function tell a coherent story.
Interviewer: Protein dynamics has become increasingly important in your recent work. Why?
Stefano Ciurli: Because structure alone is not enough. A protein is not a statue. Metal binding can reorganize a protein without producing a dramatic structural rearrangement. It can change compactness, diffusion, local flexibility, or the energetic landscape. In systems such as HypA, nickel binding appears to induce a more compact and globally rigidified state, while leaving many fast internal motions relatively similar. That kind of result is subtle but mechanistically meaningful. It tells us that metal binding may prepare a protein for interaction, transfer, or regulation without requiring a large conformational switch.
Interviewer: Is there a central idea that has guided your work?
Stefano Ciurli: Perhaps the idea that metal ions are not merely cofactors. They are organizers of biological function. They shape protein structure, catalysis, regulation, and cellular adaptation. To understand a metalloenzyme, one must understand not only the active site, but also how the cell builds it, protects it, and uses it. That broader view has guided much of my career.
Interviewer: Looking back, do you see continuity between your earliest training and your mature work on urease and nickel trafficking?
Stefano Ciurli: Absolutely. The systems changed, the methods expanded, and the biological questions became broader, but the core remained the same. My early training taught me to respect the chemistry of the metal site. Later, I learned to place that chemistry inside the protein, then inside the cell. Urease maturation, nickel trafficking, HypA, UreE, and metal homeostasis are all extensions of that original fascination with how metal ions are controlled by molecular architecture.
Interviewer: What changes have you seen in bioinorganic chemistry during your career?
Stefano Ciurli: The field has become more integrated and more biological. Earlier, much attention was devoted to understanding metal sites and model complexes, which remains essential. But today we increasingly ask how metals function in cellular networks: how they are trafficked, how they influence virulence, how they contribute to disease, and how they can be targeted therapeutically. At the same time, structural methods, computational biology, omics approaches, and advanced spectroscopy have expanded what we can study. The field is broader, but also more connected.
Interviewer: You have also played an important editorial role in the field. How has that shaped your perspective?
Stefano Ciurli: Editorial work gives you a broad view of a discipline. You see how the field changes, which questions become central, which methods mature, and how standards evolve. It also teaches responsibility. A journal is not only a place where papers are collected; it is a community instrument. As editors, we have to promote rigor, fairness, and scientific quality. That experience has reinforced my belief that bioinorganic chemistry is a vibrant and evolving field.
Interviewer: What do you consider one of the most rewarding aspects of your scientific career?
Stefano Ciurli: I would say the possibility of building connections: between chemistry and biology, between young scientists and mature research questions, between local expertise and international collaborations. Science is not only the production of data. It is also the construction of a scientific culture. Training students and postdocs, watching them become independent, and seeing ideas evolve through collaboration has been one of the most rewarding parts of my career.
Interviewer: How did mentorship influence you?
Stefano Ciurli: Mentorship was fundamental. From different mentors I absorbed different lessons: the importance of chemical creativity, the need for rigor in inorganic chemistry, and the power of spectroscopy when applied to metalloproteins. Each mentor contributed something different. A scientific identity is often built from several influences, which one later recombines in a personal way.
Interviewer: What advice would you give to young scientists entering bioinorganic chemistry?
Stefano Ciurli: Learn chemistry deeply, but do not stop there. Learn biology, structural methods, kinetics, thermodynamics, and data analysis. Be technically rigorous, but also conceptually ambitious. Metals in biology are not isolated curiosities; they are part of complex systems. Young scientists should be comfortable moving across disciplines. And they should not be afraid of difficult proteins or difficult questions. Often, the most interesting biology is hidden in systems that are experimentally demanding.
Interviewer: What would you say more generally to young scientists in the early stage of their own career?
Stefano Ciurli: I would tell them not to rush the process of becoming independent. Learn techniques deeply, but do not become a prisoner of techniques. Learn from mentors, but do not simply imitate them. And above all, choose questions that matter. A good scientific career is not built only on productivity; it is built on coherence, rigor, and the courage to pursue difficult problems.
Interviewer: If you had to summarize the first chapter of your career, how would you describe it?
Stefano Ciurli: It was a journey from inorganic chemistry to biology, but without abandoning chemistry. I began with metal complexes and clusters, moved through metalloprotein spectroscopy, and eventually arrived at the biological machinery of metal-dependent enzymes. In retrospect, the path seems logical. At the time, it was simply curiosity leading from one question to the next.
Interviewer: Finally, how would you like your scientific career to be remembered?
Stefano Ciurli: I would be happy if it were remembered as a contribution to understanding how metals make biology possible. More specifically, I hope my work has helped clarify how nickel enzymes are assembled, regulated, and connected to microbial physiology. But beyond individual discoveries, I would like to be remembered for having helped train scientists, strengthen bioinorganic chemistry, and show that careful mechanistic work can illuminate fundamental biological processes.
Closing Note
Stefano Ciurli’s career exemplifies the spirit of bioinorganic chemistry: rigorous, interdisciplinary, and deeply attentive to the molecular logic by which metals sustain life. From early training in inorganic chemistry to major contributions on nickel enzymes, urease maturation, metallochaperones, protein dynamics, and metal homeostasis, his work reflects a constant commitment to understanding how inorganic elements become biological function.
His scientific path also illustrates a broader lesson: bioinorganic chemistry is not simply the study of metals in proteins, but the study of how life organizes chemistry. Through research, mentorship, collaboration, and editorial leadership, Stefano Ciurli has helped define that vision for several generations of scientists.
